HP D2D Backup Concepts & Guide

HP StoreOnceBackup systems Concepts and ConfigurationGuidelines

AbstractIf you are new to the HP StoreOnce Backup System, read this guide before you configure your system. It provides network andFibre Channel configuration guidelines, describes the StoreOnce VTL, NAS, StoreOnce Catalyst and Replication technologyand advises how to plan the workload being placed on the HP StoreOnce Backup System in order to optimize performanceand minimize the impact of backup, deduplication, replication and housekeeping operations competing for resources. Theinformation in this guide is valid for both single-node and multi-node G3 StoreOnce Backup systems, running software version3.6.0 and later.

IMPORTANT: Always check http://www.hp.com/support/manuals for the most up-to-date documentation for your product.

HP Part Number: BB877-90913Published: November 2013Edition: 4

http://www.hp.com/support/manuals

© Copyright 2011 — 2013 Hewlett-Packard Development Company, L.P.

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The information contained herein is subject to change without notice. The only warranties for HP products and services are set forth in the expresswarranty statements accompanying such products and services. Nothing herein should be construed as constituting an additional warranty. HP shallnot be liable for technical or editorial errors or omissions contained herein.

WARRANTY STATEMENT: To obtain a copy of the warranty for this product, see the warranty information website:

http://www.hp.com/go/storagewarranty

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Revision History

November 2011Revision 1This is the first edition, issued with the launch of the HP StoreOnce B6200 Backup system.

May 2012Revision 2This is the second edition, issued with the 3.3.x version of HP StoreOnce software.

May 2013Revision 3This is the third edition, issued with the 3.6.0 version of HP StoreOnce software. It has been expanded to include information about new modelsand also now contains generic information from the separate document HP StoreOnce Backup system best practices for VTL, NAS, StoreOnceCatalyst and Replication implementations.

October 2013Revision 4This is the fourth edition, issued with the 3.9.0 version of the HP StoreOnce software. It has been updated to include new models, HP StoreOnce2700, 4500 and 4700 Backup.

http://www.hp.com/go/storagewarranty

Contents1 Before you start..........................................................................................7

Overview................................................................................................................................7HP StoreOnce Backup system models..........................................................................................7StoreOnce Catalyst targets for backup applications.......................................................................8NAS targets for backup applications...........................................................................................9Virtual Tape Library targets for backup applications......................................................................9Comparing StoreOnce Catalyst, NAS and Virtual Tape Library target devices...................................9Networking and Fibre Channel considerations...........................................................................10Licensing...............................................................................................................................11Security Features....................................................................................................................12For more information...............................................................................................................13

2 HP StoreOnce technology..........................................................................14Data deduplication.................................................................................................................14

Key performance factors with deduplication that occurs on the StoreOnce Backup system............14VTL and NAS Replication overview...........................................................................................15

Key performance factors with replication...............................................................................15Catalyst Copy and deduplication..............................................................................................15Housekeeping........................................................................................................................15Backup Application considerations............................................................................................16

Multi-stream or multiplex, what do they mean?.......................................................................16Why multiplexing is a bad practice......................................................................................16Effect of multiple streams on StoreOnce Performance .............................................................18Data compression and encryption backup application features................................................21

3 Concepts specific to StoreOnce B6200 Backup system..................................22The HP StoreOnce B6200 Backup system...................................................................................22B6200 Basic Concepts............................................................................................................23Deployment choices................................................................................................................25

4 Networking considerations........................................................................27Common networking considerations..........................................................................................27

Supported Ethernet configurations........................................................................................27Network bonding modes....................................................................................................28

Network configuration in single-node StoreOnce Backup systems..................................................28General guidelines.............................................................................................................29Single port configurations...................................................................................................30Dual port configurations.....................................................................................................31Bonded port configurations (recommended)..........................................................................3210GbE Ethernet ports on StoreOnce Backup systems...............................................................33Network configuration for CIFS AD......................................................................................33

Option 1: HP StoreOnce Backup system on Corporate SAN and Network SAN.....................34Option 2: HP StoreOnce Backup system on Network SAN only with Gateway.......................35

5 Network configuration in multi-node StoreOnce Backup systems......................36What is currently supported.....................................................................................................36What is not currently supported................................................................................................36Supported network configurations (templates).............................................................................36

Gateway considerations.....................................................................................................37Template 1, uses 10 GbE and 1 GbE sub-nets........................................................................37Template 2, uses 1GbE network only....................................................................................38Template 3, uses 10GbE network only..................................................................................39Template 4, uses two 1GbE networks...................................................................................39

Contents 3

Template 5, uses 1GbE network only....................................................................................406 Fibre Channel considerations.....................................................................41

Port assignment for StoreOnce Backup systems with two Fibre Channel cards..................................41General Fibre Channel configuration guidelines..........................................................................42

Switched fabric..................................................................................................................42Direct Attach (private loop)..................................................................................................44Zoning.............................................................................................................................44

Use soft zoning for high availability.................................................................................45Diagnostic Fibre Channel devices.............................................................................................46

7 Configuring FC to support failover in a StoreOnce B6200 Backup systemenvironment................................................................................................47

Autonomic failover..................................................................................................................47What happens during autonomic failover? ...........................................................................47Failover support with backup applications ............................................................................48Designing for failover ........................................................................................................49

Key Failover FC zoning considerations ......................................................................................49Fibre channel port presentations ..............................................................................................50Scenario 1, single fabric with dual switches, recommended..........................................................52Scenario 2, single fabric with dual switches, not advised.............................................................53Scenario 3, dual fabric with dual switches, recommended............................................................54

What happens if a fabric fails? ..........................................................................................55Scenario 4, dual fabric with dual switches, not advised...............................................................56

8 StoreOnce Catalyst stores..........................................................................58StoreOnce Catalyst technology.................................................................................................58

Key features......................................................................................................................58StoreOnce interfaces with StoreOnce Catalyst............................................................................59Catalyst Copy........................................................................................................................60Summary of Catalyst best practices...........................................................................................61StoreOnce Catalyst and the StoreOnce GUI...............................................................................62

Maximum concurrent jobs and blackout windows...................................................................62Client access permissions....................................................................................................63

More information....................................................................................................................649 Virtual Tape Devices.................................................................................65

Overview..............................................................................................................................65Tape Library Emulation ...........................................................................................................65

Emulation types.................................................................................................................65Cartridge sizing.................................................................................................................66Number of libraries per appliance.......................................................................................66

Backup application and configuration.......................................................................................66Blocksize and transfer size..................................................................................................66

Rotation schemes and retention policy.......................................................................................67Retention policy.................................................................................................................67Rotation scheme.................................................................................................................67

Summary of VTL best practices.................................................................................................6810 NAS shares...........................................................................................70

Operating system support........................................................................................................70Backup application support......................................................................................................70Shares and deduplication stores...............................................................................................70

Maximum concurrently open files.........................................................................................71Maximum number of NAS shares.........................................................................................71Maximum number of files per NAS share and appliance........................................................71Maximum number of users per CIFS share.............................................................................72

4 Contents

Maximum number of hosts per NFS share ............................................................................72CIFS share authentication....................................................................................................72

Backup application configuration..............................................................................................72Backup file size..................................................................................................................73Disk space pre-allocation....................................................................................................74Block/transfer size.............................................................................................................74Concurrent operations........................................................................................................74Buffering...........................................................................................................................74Overwrite versus append....................................................................................................74Compression and encryption...............................................................................................75Verify...............................................................................................................................75Synthetic full backups.........................................................................................................75

Summary of NAS best practices...............................................................................................7511 Replication.............................................................................................77

What is replication?................................................................................................................77StoreOnce VTL and NAS replication overview............................................................................78Replication usage models (VTL and NAS)..................................................................................78What to replicate...................................................................................................................81Appliance library and share replication fan in/fan out................................................................82Concurrent replication jobs......................................................................................................82Apparent replication throughput...............................................................................................82What actually happens in replication?......................................................................................83Limiting replication concurrency................................................................................................83WAN link sizing....................................................................................................................83Seeding and why it is required.................................................................................................84

Replication models and seeding..........................................................................................85Controlling Replication ...........................................................................................................86

Replication blackout windows..............................................................................................87Replication bandwidth limiting.............................................................................................87Source appliance permissions..............................................................................................88

12 Seeding methods in more detail................................................................89Seeding over a WAN link.......................................................................................................89Co-location (seed over LAN)....................................................................................................92Floating StoreOnce seeding.....................................................................................................94Seeding using physical tape or portable disk drive......................................................................95

13 Implementing replication with the HP B6200 Backup system.........................98Active/Passive and Active/Active configurations.........................................................................98Many to One configurations..................................................................................................102

Implementing floating StoreOnce seeding...........................................................................102Balancing Many-to-One replication....................................................................................103Replication and load balancing.........................................................................................104

14 Housekeeping......................................................................................106Housekeeping Blackout window.............................................................................................106Tuning housekeeping using the StoreOnce GUI.........................................................................106

15 Tape Offload.......................................................................................109Terminology.........................................................................................................................109

Direct Tape Offload.........................................................................................................109Backup application Tape Offload/Copy from StoreOnce Backup system.................................109Backup application Mirrored Backup from Data Source.........................................................109Tape Offload/Copy from StoreOnce Backup system versus Mirrored Backup from Data Source...110

When is Tape Offload required?............................................................................................110Catalyst device types........................................................................................................110

Contents 5

VTL and NAS device types................................................................................................111HP StoreOnce Optimum Configuration for Tape Offload............................................................112Offload Considerations.........................................................................................................112

VTL Cloning/Media Copy to Physical Tape.........................................................................112HP StoreEver Tape Libraries...............................................................................................113Backup Application..........................................................................................................113

HP StoreOnce Optimum Tape Offload Configuration.................................................................11316 Key parameters....................................................................................115

StoreOnce B6200 Backup.....................................................................................................115StoreOnce 2700, 4500 and 4700 Backup...............................................................................116StoreOnce 2610/2620, 4210/4220 and 4420/4430 Backup...................................................117

About this guide........................................................................................120Intended audience................................................................................................................120Related documentation..........................................................................................................120Document conventions and symbols........................................................................................120HP technical support.............................................................................................................121HP websites.........................................................................................................................121Documentation feedback.......................................................................................................121

6 Contents

1 Before you startOverview

The HP StoreOnce Backup System is a disk-based storage appliance for backing up host networkservers or PCs to target devices on the appliance. These devices are configured as Network-AttachedStorage (NAS), StoreOnce Catalyst or Virtual Tape Library (VTL) targets for backup applications.The total number of backup target devices provided by an HP StoreOnce Backup System variesaccording to model. These devices may be all Storeonce Catalyst, all VTL, all NAS or anycombination of Catalyst, NAS and VTL devices. All HP StoreOnce devices automatically make useof StoreOnce deduplication, ensuring efficient and cost-effective use of disk space. A further benefitof StoreOnce Catalyst devices is that deduplication may be configured to occur on the MediaServer (low bandwidth) or on the StoreOnce Backup system (high bandwidth), allowing the userto decide which makes most efficient use of available bandwidth.

HP StoreOnce Backup system modelsThe information in this guide relates to all G3 HP StoreOnce Backup system models. (G3 meansthat the systems are running StoreOnce software version 3.x.x.)These products are also sometimes referred to as multi-node or single-node Backup systems, whichrelates to the hardware configuration.• The HP StoreOnce B6200 Backup system is the multi-node model and is composed of 1 to 4

couplets (the number depends on the customer-specific configuration). A couplet is a pairedcombination of two nodes (or servers) that are directly connected in failover pairs. Within acouplet each node has access to and can assume the role of both nodes in the event of nodefailure. A couplet provides a minimum of storage and this can be expanded in increments byadding pairs of 12–disk storage shelves up to a maximum of three pairs per couplet.

• All other HP StoreOnce Backup systems are single-node models and are composed of a singleserver. Some models support expansion using 12–disk storage shelves.

Table 1 StoreOnce B6200 models

Storage expansionPortsDescriptionProduct model

Up to six 12–disk storageshelves per couplet (threeper node)

8 x 1GbE portsnl

4 x 10GbE portsnl

8 x FC ports

Rack system with up to fourcouplets. Each coupletcontains two nodes (servers)and two 12–disk RAIDstorage controllers

HP StoreOnce B6200Backup, EJ022A

Table 2 StoreOnce 2700/ 4500, 4700

Storage expansionPortsInterfaces supportedDescriptionProduct model

Not supported4 x 1GbE portsiSCSI onlyA single server withfour 2TB hot-plug disks

HP StoreOnce 27008TB Backup , BB877A

One 12–diskexpansion shelf,BB881A

4 x 1GbE portsnl

2 x 10GbE portsnl

2 x FC ports

iSCSI and FCA single server withtwelve 2TB hot-plugdisks

HP StoreOnce 450024TB Backup,BB878A

Overview 7

Table 2 StoreOnce 2700/ 4500, 4700 (continued)


Up to seven 12–diskexpansion shelves,BB881A

4 x 1GbE portsnl

2 x 10GbE portsnl

4 x FC ports

iSCSI and FCA head server unitwith two 1TB disksand a pre-configuredstorage array withtwelve 2TB disks

HP StoreOnce 470024TB Backup,BB879A

Up to five 11–diskexpansion kits for the

4 x 1GbE portsnl

4 x 10GbE portsnl

iSCSI and FCA head server unitwith two 1TB disksand a pre-configured

HP StoreOnce 490048TB Backup,BB903A disk enclosure,

BB908Anl

4 x FC portstwo-drawer diskenclosure with eleven One additional disk

enclosure with 11+44TB disks and four hotspare disks spare pre-configured

storage, BB904A

Table 3 StoreOnce 2620. 4210, 4220, 4420 and 4430 models


Not supported2 x 1GbE portsiSCSI onlyA single server withfour 1TB disks

HP StoreOnce 2620Backup , BB852A

One 12–diskexpansion shelf

2 x 1GbE ports 2 xFC ports

iSCSI ( BB853A)or FC(BB854A)

A single server withtwelve 1TB disks (seenote below)

HP StoreOnce 4210Backup, BB853A andBB854A


4 x 1GbE ports 2 xFC ports

iSCSI and FCA single server withtwelve 1TB disks

HP StoreOnce 4220Backup, BB855A


2 x 1GbE ports 2 x10GbE ports2 x FCports



Up to three 12–diskexpansion shelves

2 x 1GbE ports 2 x10GbE ports2 x FCports



NOTE: There are other legacy HP StoreOnce products, running StoreOnce software 2.x.x and1.x.x. This guide should not be used with those products.

StoreOnce Catalyst targets for backup applicationsNOTE: See Catalyst devices (page 58) for a more detailed description of StoreOnce Catalysttechnology and best practices.

HP StoreOnce Catalyst is a unique interface and is fundamentally different from virtual tape orNAS. It provides the backup application with full control of backup and replication (called CatalystCopy).HP StoreOnce Catalyst allows:

• Backup applications to back up data to a target store on the HP StoreOnce Backup system.Deduplication may occur on the media server or on the HP StoreOnce Backup system.

• Backup applications to copy jobs between HP StoreOnce Backup systems. All configurationis carried out from the backup application, which makes this an attractive alternative to usingthe replication function on the HP StoreOnce Backup system.

This function requires a backup application that supports HP StoreOnce Catalyst. For up-to-datedetails on supported applications refer to http://www.hp.com/go/ebs.

8 Before you start

http://www.hp.com/go/ebs

For supported Symantec backup products, a plug-in application (HP OST 2.0) is required on eachbackup application media server that will use the Catalyst functionality. This can be downloadedfrom the Software Storage section of your StoreOnce product's Download drivers and softwarepage on http://www.hp.com/support/downloads.OST/Catalyst devices require a license to be used at both source and target – but do NOT requirean additional Catalyst Copy license as well. On the HP StoreOnce B6200 Backup system Catalystlicensing is per couplet; if a system has multiple couplets and one couplet is not using Catalyststores, you do not need a license for that couplet.

IMPORTANT: Much of the information that is displayed on the HP StoreOnce Catalyst pages istaken directly from the backup application. It is strongly recommended to give jobs and mediaserver groupings names on the backup application that will also be meaningful when they aredisplayed in the StoreOnce Catalyst pages.

NAS targets for backup applicationsNOTE: See NAS shares (page 70) for more detailed information about NAS shares and bestpractices.

Support for both CIFS and NFS protocols means that NAS target devices may be created as backuptargets for both Windows and UNIX/Linux hosts, and may be used with most backup applicationsthat support backup to disk. NAS targets on an HP StoreOnce Backup System provide networkfile share access that is optimized for backup to disk. They should not be used for general purposefile storage.There are no licensing requirements for backup to NAS targets, but a replication license is requiredwhen replicating NAS targets to another StoreOnce Backup system.

Virtual Tape Library targets for backup applicationsNOTE: See Virtual Tape Devices (page 65) for more detailed information about VTL devices andbest practices.

The backup target appears to the host as an Ultrium Tape Library and requires a backup applicationthat supports backup to tape. Tape Library emulation type is selected during initial configurationand this determines the number of cartridge slots and embedded tape drives that may be configuredfor the device.Virtual Tape Libraries provide considerable flexibility for a variety of backup rotation schemes.

• The HP B6200 Backup system may only be configured with Fibre Channel (FC) devices.

• The single node products may be configured with iSCSI and Fibre Channel (FC) devices,although some only support iSCSI.

NOTE: The HP D2DBS Generic Library emulation type provides the most flexibility in numbersof cartridges and drives. It is also clearly identified in most backup applications as a virtual tapelibrary and so is easier for supportability. If your backup application supports this emulation type,it is the recommended option.

There are no licensing requirements for backup to VTL targets, but a replication license is requiredwhen replicating VTL targets to another StoreOnce Backup system.

Comparing StoreOnce Catalyst, NAS and Virtual Tape Library targetdevices

The following table summarizes some of the differences between StoreOnce Catalyst, NAS shareand Virtual Tape device types.

NAS targets for backup applications 9

http://www.hp.com/support/downloads

Table 4 Comparing StoreOnce Catalyst, NAS and Virtual Tape device types

CommentsBest Used InKey FeaturesDevice Type

Tried and tested, wellunderstood with traditional

Enterprise FC SANenvironment (some models

Uses virtual tape drives andvirtual slots to emulatephysical tape libraries

Virtual Tape (VTL)

backup applications Usesdo not support FC). HPRobot and Drives devicetype

StoreOnce also supportsiSCSI VTL (not B6200)

This is a NAS target forbackup - not recommended

Specific environments thatdo not support tape

NAS shares can be easilyconfigured and viewed by

NAS (CIFS/NFS shares)

for random NAS file typeaccess.nl

emulation backup or preferto backup directly to disk. Insome cases the licensing

the operating system: CIFSshares for Windows, NFSshares for Unix Uses Basic Disk device type

may be lower cost for NASshares as a backup target.Consider this device type forvirtualized environments

May require additionalplug-in components onMedia Serversnl

Environments that require asingle management consolefor all backup andreplication activities and the

Backup software has totalcontrol over the HPStoreOnce appliance,providing source-based

StoreOnce Catalyst (stores)

Uses OpenStorage devicetype (Symantec) or Backupability to implement

federated deduplication*nl

deduplication, replicationcontrol, improved DR etc. to Disk ( HP Data Protector)

device typeWherever possible HPrecommend the use of HPStoreOnce Catalyst

* Federated deduplication is an HP term referring to the ability to distribute the deduplication loadacross Media servers. This feature is sometimes known as source-based deduplication or lowbandwidth backup.

Networking and Fibre Channel considerationsNOTE: See Networking considerations and Fibre Channel considerations for more informationabout Ethernet and FC configurations and best practices.

The following table shows which network and fibre channel ports are present on each model ofStoreOnce appliance. Correct configuration of these interfaces is important for optimal data transfer.A mixture of iSCSI and FC port virtual libraries and NAS shares can be configured on the sameStoreOnce appliance to balance performance needs if required.

• The HP StoreOnce B6200 Backup system does not support iSCSI virtual libraries.

• The HP StoreOnce 2700, 2620 and 4210 iSCSI Backup systems do not support FC virtuallibraries.

Table 5 Single node systems, ethernet and FC ports

Fibre Channel ConnectionEthernet ConnectionProduct NumberProduct/Model Name

None2 x 1GbEnl

BB877AStoreOnce 2700

2 x 8GB FC4 x 1GbEnl

BB878AStoreOnce 45002 x 10GbE



None2 x 1GbEnl


None2 x 1GbEnl

BB853AStoreOnce 4210 iSCSI


BB854AStoreOnce 4210 fc

10 Before you start

Table 5 Single node systems, ethernet and FC ports (continued)

Fibre Channel ConnectionEthernet ConnectionProduct NumberProduct/Model Name







For multi-node systems, the number of network and FC ports depends upon the number of coupletsand racks installed. There is a minimum of one couplet and one rack.

Table 6 Multi node systems, HP B6200, ethernet and FC ports

Fibre Channel ConnectionEthernet ConnectionNodeCouplet


Node 1Couplet 1 in Rack 12 x 8GB FC2 x 10GbE


Node 22 x 8GB FC2 x 10GbE













Licensing

Licensing requirementsThe HP StoreOnce Backup system has the following licensing requirements:

• Each storage shelf arrives with a license that must be loaded, further capacity upgrades alsoarrive with a license included.

• There is no licensing required for VTL or NAS emulations.

• VTL and NAS replication requires a license on the target site (B6200: per couplet, but only ifVTL/NAS replication is used on that couplet..

• OST/Catalyst devices require a license to be used at both source and target – but DO NOTrequire an additional replication license as well. B6200: Catalyst licensing is per couplet; ifa couplet is not using Catalyst stores – you do not need the license.

• Security features (Data at Rest Encryption and Secure Erase) require a security license.

NOTE: Licenses can only be applied from the StoreOnce CLI. See the HP StoreOnce CLI UserGuide for more information.

Licensing 11

Types of licensingThere are two types of licensing:• Full license (not time limited)

• Instant on (time limited to 90 days): This allows you to try out licensable functionality onStoreOnce hardware products before paying for a full license for features such as ReplicationTarget, Catalyst, or the Security features of Data at Rest Encryption and Secure Erase. Formore information on applying this type of license, see the HP StoreOnce backup systemInstallation and Configuration guide and the HP StoreOnce Backup system CLI ReferenceGuide.

Security FeaturesThe HP StoreOnce backup system offers two security features that can be applied using a Securitylicense: Data at Rest Encryption and Secure Erase.

Data at Rest EncryptionWhen enabled, the Data at Rest Encryption security feature protects data at rest on a stolen,discarded, or replaced disk from forensic attack. Data encryption is only available on Catalystand VTL devices.When you create a new store or library (VTL or Catalyst), you have the option to enable encryptionif the security features license has already been applied. Once enabled, encryption will automaticallybe performed on the data before it is written to disk. Encryption cannot be disabled once it hasbeen set for a library or Catalyst store.When you create an encrypted store or library, the key store is updated with the encryption key.This keystore may be backed up and saved securely offsite in case the original key store is corrupted.However, be sure to keep only the latest version of the key store as a backup; the key store on theStoreOnce Backup system is updated each time you create a library or Catalyst store. The StoreOnceCLI command that backs up the key store also encrypts it, ensuring that it can only be decryptedby the HP StoreOnce backup system, should you need to restore it. Be very diligent about backingup your keystore if you are creating encrypted stores or libraries! See the HP StoreOnce Backupsystem CLI Reference Guide for more information about the StoreOnce CLI commands for backingup and restoring key stores.

NOTE: Each library or Catalysts store configured will use a different key. The StoreOnce softwareautomatically tracks which key is relevant to which device in the Key Store File. Keys areautomatically re-applied to the right device if the key store file is restored.

IMPORTANT: B6200 systems: Every time that you expand storage by adding a couplet, you willneed to restore your keystore. Installing the additional couplet is an HP Support task, but you areresponsible for ensuring that a Security license has been installed for the new couplet and savingthe existing keystore.

Secure eraseSecure Erase can be enabled for all store types. When enabled, this feature allows you to securelyerase data that has been backed up as part of a regular backup job. The Secure Erase featurecan only be enabled after store or library creation (edit the store or library to enable Secure Erase).All data written to disk once secure erase is enabled will be securely erased upon data deletion.For example, you may have unintentionally backed up confidential data and need to be sure thatit has been securely erased. You must work with your backup application to trigger the secureerase, for example by forcing a format of a cartridge. The backup application sends the requestto delete the data and the deletion is carried out as part of the Housekeeping function.

12 Before you start

NOTE: If you need to immediately remove data, you must make sure your backup applicationis configured correctly. Rotation and retention policies may need to be revisited to ensure that thedata is expired. Also, data that has been written to a store or library without secure erase enabledwill not be able to be securely erased (there is no retroactive application of secure erase to alreadywritten data).

Only chunks that are not referenced by any other items can be securely erased. If a chunk isreferenced by another item which is not marked for secure erase, then that chunk will not be erased,securely or otherwise. You will need to utilize your backup application when enacting a secureerase on stores, shares, or libraries that have secure erase enabled.See the HP StoreOnce Backup system User Guide for information on how to apply the Securitylicense for these features.

For more informationSeparate chapters in this guide provide more background information about Network and FibreChannel configuration; StoreOnce Catalyst, VTL and NAS devices and the specifications that aresupported; and replication, housekeeping and tape offload.The following documents are also available:

• HP StoreOnce user guides (PDF): There are separate user guides for the single node and themulti node models. They describe how to use the StoreOnce GUI.

• HP StoreOnce CLI Reference Guide (PDF): This guide describes the StoreOnce CLI commandsand how to use them.

• HP StoreOnce Linux and UNIX Configuration Guide (PDF): This guide contains informationabout configuring and using HP StoreOnce Backup systems with Linux and UNIX.

• HP StoreOnce B6000 Series Backup system Installation Planning and Preparation Guide andChecklists (PDF): This guide is the site installation preparation and planning guide for the HPStoreOnce B6200 Backup system only. It contains checklists that should be completed priorto HP service specialists arriving on site to install the product.

• HP StoreOnce 2620, 4210/4220 and 4420/4430 Backup system Installation andConfiguration Guide (PDF): This guide is the installation and configuration guide for thesingle-node HP StoreOnce Backup systems.

• HP StoreOnce Backup system Capacity Upgrade booklet (PDF): This guide describes how toinstall the capacity upgrade kits.

• HP StoreOnce Backup systems Summary of Best practices for VTL, NAS, StoreOnce Catalystand Replication implementations with sizing and application configuration examples (PDF):This document contains much of the same information as this guide, but it also contains aworked examples for sizing a VTL, NAS and StoreOnce Catalyst solution and implementingStoreOnce Catalyst with supported backup applications.

You can find these documents from the Manuals page of the HP Business Support Center website:http://www.hp.com/support/manuals

In the Storage section, click Storage Solutions and then select your product.

For more information 13


2 HP StoreOnce technologyA basic understanding of the way that HP StoreOnce Technology works is necessary in order tounderstand factors that may impact performance of the overall system and to ensure optimalperformance of your backup solution.

Data deduplicationHP StoreOnce Technology is an “inline” data deduplication process. It uses hash-based chunkingtechnology, which analyzes incoming backup data in “chunks” that average 4K in size. The hashingalgorithm generates a unique hash value that identifies each chunk and points to its location in thededuplication store.Hash values are stored in an index that is referenced when subsequent backups are performed.When data generates a hash value that already exists in the index, the data is not stored a secondtime, but rather a count is increased showing how many times that hash code has been seen.Unique data generates a new hash code and that is stored on the appliance. Typically about 2%of every new backup is new data that generates new hash codes.With Virtual Tape Library and NAS shares, deduplication always occurs on the StoreOnce Backupsystem. With Catalyst stores, deduplication may be configured to occur on the media server(recommended) or on the StoreOnce Backup system.

Key performance factors with deduplication that occurs on the StoreOnce Backupsystem

The inline nature of the deduplication process means that it is a very processor and memory intensivetask. HP StoreOnce appliances have been designed with appropriate processing power andmemory to minimize the backup performance impact of deduplication.

• Best performance will be obtained by configuring a larger number of libraries/shares/Catalyststores with multiple backup streams to each device, although this has a trade off with overalldeduplication ratio.

◦ If servers with lots of similar data are to be backed up, a higher deduplication ratio canbe achieved by backing them all up to the same library/share/Catalyst store, even if thismeans directing different media servers to the same data type device configured on theStoreOnce appliance.

◦ If servers contain dissimilar data types, the best deduplication ratio/performancecompromise will be achieved by grouping servers with similar data types together intotheir own dedicated libraries/shares/Catalyst stores. For example, a requirement to backup a set of exchange servers, SQL database servers, file servers and application serverswould be best served by creating four virtual libraries, NAS shares or Catalyst stores;one for each server data type.

• The best backup performance to a device configured on a StoreOnce appliance is achievedusing somewhere below the maximum number of streams per device (the maximum numberof streams varies between models

• When restoring data from a deduplicating device it must reconstruct the original un-deduplicateddata stream from all of the data chunks contained in the deduplication stores. This can resultin lower performance than that of the backup process (typically 80%). Restores also typicallyuse only a single stream.

• Full backup jobs will result in higher deduplication ratios and better restore performance.Incremental and differential backups will not deduplicate as well.

14 HP StoreOnce technology

VTL and NAS Replication overviewDeduplication technology is the key enabling technology for efficient replication because only thenew data created at the source site needs to replicate to the target site once seeding is complete.This efficiency in understanding precisely which data needs to replicate can result in bandwidthsavings in excess of 95% compared to having to transmit the full contents of a cartridge/sharefrom the source site. The bandwidth saving will be dependent on the backup data change rate atthe source site.There is some overhead of control data that also needs to pass across the replication link. This isknown as manifest data, a final component of any hash codes that are not present on the remotesite and may also need to be transferred. Typically the “overhead components” are less than 2%of the total virtual cartridge/file size to replicate.Replication throughput can be “throttled” by using bandwidth limits as a percentage of an existinglink, so as not to affect the performance of other applications running on the same WAN link.

Key performance factors with replicationKey factors for performance considerations with replication:• Define your “seeding” (first replication) strategy before implementation – several methods are

available depending on your replication model active/passive, active/active or Many-to-One.See Seeding methods in more detail.

• If a lot of similar data exists on remote office StoreOnce libraries, replicating these into asingle target VTL library will give a better deduplication ratio on the target StoreOnce Backupsystem. Consolidation of remote sites into a single device at the target is available with VTLdevice types. (Catalyst targets can also be used to consolidate replication from various sourcesites into a single Catalyst store at a DR site.)

• Replication starts when the cartridge is unloaded or the NAS share file is closed and when areplication window is enabled. If a backup spans multiple cartridges or NAS files, replicationwill start on the first cartridge/ file as soon as the job spans to the second, unless a replicationblackout window is in force.

• Size the WAN link appropriately to allow for replication and normal business traffic takinginto account data change rates. A temporary increase in WAN speed may be desirable forinitial seeding process if it is to be performed over the WAN

• Apply replication bandwidth limits or apply replication blackout windows to prevent bandwidthhogging. The maximum number of concurrent replication jobs supported by source and targetStoreOnce appliances can be varied in the StoreOnce Management GUI to also managethroughput and bandwidth utilization.

Catalyst Copy and deduplicationCatalyst Copy is the equivalent of Virtual library and NAS share replication. The same principlesapply in that only the new data created at the source site needs to be copied (replicated) to thetarget site. The fundamental difference is that the copy jobs are created by the backup applicationand can, therefore, be tracked and monitored within the backup application catalog as well asfrom the StoreOnce Management GUI. Should it be necessary to restore from a Catalyst copy, thebackup application is able to restore from a duplicate copy without the need to re-import data tothe catalog database.The key performance factors are the same as the replication performance factors.

HousekeepingHousekeeping is an important process in order to maximize the deduplication efficiency of theappliance. If data is deleted from the StoreOnce system (e.g. a virtual cartridge is overwritten orerased), any unused chunks will be marked for removal, so space can be freed up (space

VTL and NAS Replication overview 15

reclamation). The process of removing chunks of data is not an inline operation because this wouldsignificantly impact performance. This process, termed “housekeeping”, runs on the appliance asa background operation.Housekeeping is triggered in different ways depending on device type and backup application:

• VTL: media on which the data retention period has expired will be overwritten by the backupapplication. The act of overwriting triggers the housekeeping of the expired data. If media isnot overwritten (if backup application chooses to use blank media in preference to overwriting),the expired media continues to occupy disk space.

• NAS shares: Some backup applications overwrite with the same file names after expiration;others do an expiry check before writing new data to the share; others might do a quota checkbefore overwriting. Any of these actions triggers housekeeping.

• Catalyst stores: The backup application clean-up process, the running of which is configurable,regularly checks for expired backups and removes catalog entries. This provides a much morestructured space reclamation process.

See Housekeeping (page 106) for more information about configuring housekeeping and bestpractices.

Backup Application considerations“Multiplexing” data streams from different sources into a single stream in order to get higherthroughput used to be a common best practice when using physical tape drives. This was a necessityin order to make the physical tape drive run in streaming mode, especially if the individual hostscould not supply data fast enough. But multiplexing is not required and is in fact a BAD practiceif used with HP StoreOnce StoreOnce deduplication devices.

Multi-stream or multiplex, what do they mean?Multi-streaming is often confused with Multiplexing; these are however two different (but related)terms. Multi-streaming is when multiple data streams are sent to the StoreOnce Backup systemsimultaneously but separately. Multiplexing is a configuration whereby data from multiple sources(for example multiple client servers) is backed up to a single tape drive device by interleavingblocks of data from each server simultaneously and combined into a single stream. Multiplexingis a hangover from using physical tape device, and was required in order to maintain goodperformance where source servers were slow because it aggregates multiple source server backupsinto a single stream.A multiplexed data stream configuration is NOT recommended for use with a StoreOnce systemor any other deduplicating device. This is because the interleaving of data from multiple sourcesis not consistent from one backup to the next and significantly reduces the ability of the deduplicationprocess to work effectively; it also reduces restore performance. Care must be taken to ensure thatmultiplexing is not happening by default in a backup application configuration. For example whenusing HP Data Protector to back up multiple client servers in a single backup job, it will default towriting four concurrent multiplexed servers in a single stream. This must be disabled by reducingthe “Concurrency” configuration value for the tape device from 4 to 1.

Why multiplexing is a bad practiceHP StoreOnce Backup systems rely on very similar repetitive data streams in order to de-duplicatedata effectively. When multiplexing is deployed the backup data streams are not guaranteed tobe similar, since the multiplexing can jumble up the data streams from one backup to the nextbackup in different ways – hence drastically reducing the deduplication ratios.There is no need for multiplexing to get higher performance – quite the contrary, because the bestway to get performance from any HP StoreOnce Backup system is to send multiple streams inparallel. Sending only a single multiplexed stream actually reduces performance.


The figure below shows a single backup job from multiple hosts, where the backup data is radicallydifferent from one backup job to the next. There is also only a single stream to the device on theStoreOnce Backup system. This configuration produces slow performance and poor deduplicationratios.

Figure 1 Multiplexing produces slow performance and poor dedupe ratios

Instead of multiplexing data into a single stream and sending it to the HP StoreOnce Backup system,you should re-specify the multiplexed backup job to be either a single backup job using multipledevices or multiple jobs to separate devices. This will ensure better throughput and deduplicationratios.Finally, multiplexing creates SLOWER restores because data to an individual host has to bede-multiplexed from the data stored on the device. NOT using multiplexing will actually improverestore performance.The next figure shows the recommended configuration where single or multiple jobs are streamedin parallel with little change between backup jobs. There are multiple streams to devices on theHP StoreOnce Backup system, resulting in higher performance and good deduplication ratios.

Backup Application considerations 17

Figure 2 Recommended configuration using multiple streams

Effect of multiple streams on StoreOnce PerformanceThe following graph, illustrates the relationship between the number of active data streams andperformance; the appliance is assumed to be one of the larger models where more than 24 streams(if fast enough) can achieve best throughput. The throughput values shown are for example only.Along the x axis is the number of concurrent streams. A stream is a data path to a device configuredon StoreOnce; on VTL it is the number of virtual tape drives, on NAS the number of writers, onCatalyst stores the number of streams.Along the Y axis is the overall throughput in MB/sec that the StoreOnce device can process – thisultimately dictates the backup window. As a backup window begins, the number of streamsgradually increases and we aim to have as many streams running as possible to get the bestpossible throughput to the StoreOnce device. As the backup jobs come to an end, the stream countstarts to decrease and so the overall throughput to the StoreOnce device starts to reduce.The StoreOnce device itself also has a limit which we call the maximum ingest rate. In this exampleit is 1000MB/sec. The > 24 streams value is calculated using “Infinite performance hosts” tocharacterize the HP StoreOnce ingest performance.As long as we can supply around 24 data streams at the required performance levels we keepthe StoreOnce device in its “saturation zone” of maximum ingest performance.


Figure 3 Relationship between active data streams and device configuration ( VTLs shown)

Note 1: Stream source data rates will vary; some streams will be at 8, others at 50, and maybesome others at 200. This means that as the stream count increases, it will be the aggregate totalof the streams that will drive the unit to saturation, which is the goal. Some of the factors thatinfluence source data rate are the compressiblity of data, number of disks in the disk group thatis feeding the stream, RAID type and others.Note 2: With 5 streams at 100MB/Sec we do not reach the maximum throughput of the node(server), which can support 600MB/sec in this example. This is the maximum possible ingest rateof the device for a specific model based on 5 streams. This ingest rate is the maximum even ifeach stream is capable of 200MB/Sec, because it represents the maximum amount of data themachine can process.Note 3: The number of streams available varies throughout the backup window. The curverepresenting backup streams increases as the backup jobs begin ramping into the appliance (toVTL, NAS share or Catalyst store target devices) and then declines towards the finish of the backup,when throughput rates decline as backup jobs complete. This highlights the importance ofmaintaining enough backup threads from sources to ensure that, while backups are running,sufficient source “data pump” is maintained to hold the StoreOnce device in saturation.Notes for the color-coded circles:In example 1 (red circle) we are supplying much more than 24 streams (100 actually) but they areall slow hosts and the cumulative ingest rate is 800 MB/sec (below our maximum ingest rate).In example 2 (green circle) we have some high performance hosts that can supply data at a ratehigher than the StoreOnce maximum ingest rate; and so the performance is capped at 1000MB/sec.In example 3 (blue circle) we have some very high performance hosts but can only configure 5backup streams because of the way the data is constructed on the hosts. In this case the maximum


ingest of the StoreOnce appliance is 600MB/sec but we can only achieve 500 MB/sec becausethat is as fast we we can supply the data (because of stream limitations). If we could re-configurethe backups to provide more streams, we could get higher throughput.In example 4 (brown circle) we show a more realistic situation where we have a mixture of differenthosts with different performance levels. Most importantly, we have 30 streams and a total throughputcapability of 950 MB/sec, which puts us very close to the maximum ingest rate. The maximumingest rates vary according to each StoreOnce model.Typically, on the larger StoreOnce units about 48 streams spread across the configured devicesgive the best throughput; more streams only help to sustain the throughput with each stream beingthrottled appropriately. For example, if 96 streams are configured, the throughput is still the sameas if 48 streams were configured – it is just that each stream runs slower as resources are shared.Once we understand the basic streams versus performance concept we can start to apply bestpractices for the number of devices to configure.With these factors in mind we have recommended some VTL configurations for the aboveperformance examples, which are illustrated in the following graph.

Figure 4 Relationship between active data streams and device configuration ( VTLs shown)

Note2 above: In general, per device configured we get the best throughput between 12-16 streamsand the best throughput per appliance when we reach 48 streams or more. So, for 100 streams


we could configure 6 devices with say 17 streams to each or 20 devices with 5 streams to each.6 devices is preferable because:

• Less devices are easier to manage but we can still group similar data types into the samedevice

• They provide best possible throughput when we have the higher stream count to a device

Data compression and encryption backup application featuresBoth software compression and encryption will randomize the source data and will, therefore, notresult in a high deduplication ratio for these data sources. Consequently, performance will alsosuffer. The StoreOnce Backup system will compress the data at the end of deduplication processinganyway, before finally writing the data to disk.For these reasons it is best to do the following, if efficient deduplication and optimum performanceare required:

• Ensure that there is no encryption of data before it is sent to the StoreOnce appliance.

• Ensure that software compression is turned off within the backup application. Not all datasources will result in high deduplication ratios; deduplication ratios are data type dependent,change rate dependent and retention period dependent. Deduplication performance can,therefore, vary across different data sources. Digital images, video, audio and compressedfile archives will typically all yield low deduplication ratios. If this data predominantly comesfrom a small number of server sources, consider setting up a separate library/share/Catalyststore for these sources for better deduplication performance. In general, high- change ratesyield low dedupe ratios, whilst low change rates yield high dedupe ratios over the sameretention period. As you might expect – multiple full backups yield high dedeup ratios comparedto Full and Incremental backup regimes.


3 Concepts specific to StoreOnce B6200 Backup systemThe HP B6200 Backup system provides up to 8 separate nodes in a single appliance with a singlemanagement GUI for all nodes, and failover capability across nodes within the same couplet asstandard. The best practices for single-node StoreOnce Backup systems apply but significant thoughtmust also be given to mapping customer backup requirements and media servers across deviceslocated on up to 8 separate nodes.The preferred mapping approach is to segment customer data into different data types and thenmap the data types into different backup devices configured on the HP B6200 Backup system sothat each backup device is its own unique deduplication store. This approach also improvesdeduplication ratio; similar data types mean more chance of redundant data.Network and Fibre Channel configuration requires particular care to support HP autonomic failover,which is a unique enterprise class feature of the HP B6200 StoreOnce Backup system. This isdescribed in more detail in the relevant chapters of this guide. This chapter describes basic conceptsonly.

The HP StoreOnce B6200 Backup systemThe Enterprise StoreOnce B6200 Backup System is a deduplication backup appliance supportingCatalyst, VTL and NAS target devices, which provides scale-up and scale-out performance with auser capacity of up to 512 TB and throughput of up to 28 TB/hour.The architecture uses high levels of redundancy supported by 2-node couplets that allow autonomicfailover to the other node in a couplet should a failure on one node occur. Any backups will restartautomatically after failover.

Figure 5 Base couplet

2 Node B1 Disk array controller (node B)

4 Disk array controller (node A)3 Node A

The whole appliance is managed by a single graphical user interface (GUI) and also supports acommand line interface (CLI). The HP B6200 Backup System is replication compatible with existingHP StoreOnce Backup Systems and can support a fan-in of up to 384 concurrent replication streams(up to 48 per node).

22 Concepts specific to StoreOnce B6200 Backup system

B6200 Basic ConceptsFigure 6 HP StoreOnce B6200, basic concepts

The above diagram shows the basic concepts of the HP B6200 StoreOnce architecture –understanding the architecture is key to successful deployment.

• Node: This is the basic physical building block and consists of an individual server (HP Proliantserver hardware)

• Couplet: This consists of two associated nodes and is the core of the failover architecture.Each couplet has a common disk storage sub-system achieved by dual controller architectureand cross-coupled 6Gbps SAS interfaces. Each node has access to the storage subsystem ofits partner node.

• Service set: This is a collection of software modules (logical building blocks) providing VTL/NASand replication functions. Each service set can have Virtual Tape (VT), NAS and replicationconfigurations.

• Management Console: This consists of a set of software ‘agents’, each agent running on anode, only one of which is active at any one time. Each node is in communication via aninternal network. The Management Console provides a virtual IP address for the ManagementGUI and CLI. If node failure is detected, any agent may become active (first one to respond).Only ONE active Management Console agent is allowed at any one time.

• Cluster: This is a collection of 1 to n couplets. For the HP StoreOnce B6200 Backup Systemn=4. This means that a 4-couplet, 8-node configuration is the largest permitted configuration.

• Failover: This occurs within a couplet. Service sets for VTL/NAS/Replication will run on theremaining node in the couplet. • Failback: This is a manual process to restart a node afterrecovery/repair.

• VIF: This is a Virtual network Interface. Network connections to the HP B6200 Backup Systemare to virtual IP addresses. The network ports of the nodes use bonded connections and eachbonded (2 ports into 1 entity) interface has one virtual IP address. This means that if a physicalport fails, the other port in the bonded pair can be used as the data channel because the VIFis still valid. This architecture eliminates single point of hardware failure. The architecture does

B6200 Basic Concepts 23

not use LACP (Link Aggregation Control Protocol) so there are no specific network switchsettings required.

• Storage shelf: This refers to the P2000 master controller shelf (one per node) or a P2000 JBODcapacity upgrade. JBODs are purchased in pairs and up to three pairs may be added to eachcouplet. They use dual 6Gbps SAS connections for resilience.

In reality, up to 128 TB of storage is shared between two nodes in a couplet. Depending oncustomer requirements and single node best practices, it is possible to have, for example, a serviceset on node 1 that consumes 100 TB and a service set on node 2 that consumes 28 TB of theavailable 128 TB. (However, this is not best practice and not recommended.) This architecturescales dramatically and the maximum configuration can be seen below.

Figure 7 HP B6200 Backup system, maximum configuration

Note that data, replication and storage failover is always between nodes in the same couplet butthe Management Console (GUI and CLI) can failover to any node in the whole cluster.In all cases the deployment should center around what devices and services need to be configuredon each node.In the following example Node 2 has failed and Service Set 2 has failed over to Node 1. Bothservice sets are running on Node1, but backup and replication performance will be reduced. TheManagement Console that was active on Node 2 has moved to Node 3, Couplet 2. This is notsignificant; the Management Console becomes active on the first node to respond.


Figure 8 Showing Node 2, Service Set 2 failed over to Node 1

Deployment choicesThe very first deployment choice is how to use the external networking and Fibre Channelconnections that the B6200 Enterprise StoreOnce Backup System presents.

• All GbE network connections are for NAS devices, replication and device management, andare bonded pairs to provide resiliency. There are 2 x 10 GbE ports and 4 x 1GbE ports oneach node. See Network configuration in multi-node StoreOnce Backup systems (page 36)for more details.

• The Fibre Channel connections (2 x 8 Gbs) are for VTL devices and MUST be connected toa Fibre Channel switch; direct FC Connect is not supported. The switch MUST support NPIVfor the FC failover process to work. See Configuring FC to support failover with the HPStoreOnce B6200 Backup system (page 47) for more details.

The following diagram illustrates network and Fibre Channel external connections to a two-racksystem.

Deployment choices 25

Figure 9 HP B6200 Backup system, customer connections


4 Networking considerationsThe network configuration for the StoreOnce single node systems and the StoreOnce multi nodesystems has some significant differences. Since the StoreOnce multi node product supports autonomicfailover, more care is required in the network configuration to ensure optimal operation of theautonomic failover feature. The network configuration is done as part of the HP installation processfor the multi node system.Be sure to read the appropriate section in this chapter for your model. But first there are someconsiderations that are common to all models.

Common networking considerationsThe Ethernet ports are used for data transfer to iSCSI VTL devices, StoreOnce Catalyst and CIFS/NFSshares and also for replication data transfer and management access to the StoreOnce Web andCLI Management Interfaces.

NOTE: The HP StoreOnce B6200 Backup system does not support iSCSI VTL devices.

Configured backup devices and the management interfaces are all available on all network IPaddresses configured for the appliance. In order to deliver best performance when backing updata over the Ethernet ports it will be necessary to configure the appliance network ports, and alsobackup servers and network infrastructure to maximize available bandwidth to the StoreOncedevice.

Supported Ethernet configurationsThe HP StoreOnce Backup system supports a wide range of network configurations. The followinglist summarizes configuration details.

• An Ethernet connection is required for backing up to NAS shares, Catalyst stores or iSCSI VTLdevices (not B6200), and replication/Catalyst copy activities, and for all StoreOncemanagement tasks via the GUI or CLI.

• The HP StoreOnce Backup system supports IPv4 only.

• DHCP and static IP addressing are supported on single-node systems.

• The multi-node B6200 system supports static IP only.

• For single node products, networking parameters are contained within a network configurationfile.

◦ For ease of installation, a default configuration file is supplied with the StoreOnce Backupsystem. As long as LAN port 1 of the appliance is connected to a DHCP–enabled 1GbEnetwork switch, the HP StoreOnce Backup system will be immediately active on thenetwork after installation. The user then has the option of continuing to use the defaultconfiguration file or creating and activating an additional configuration file that is tailoredto their exact networking requirements.

NOTE: 100 Base-T Ethernet will limit performance.

◦ Users who do not have a DHCP-enabled 1GbE network must create and activate a networkconfiguration file before their system can become active on the network. This networkconfiguration file may use any available Ethernet port, but one must always be connected,even if you are only using the FC ports to back up and restore data to the HP StoreOnceBackup system. This is because the network is used to access the StoreOnce ManagementConsole remotely; it is also used for replication.

Common networking considerations 27

• For the HP B6200 Backup system, networking parameters are specified within the selectednetwork template.

• All StoreOnce Backup systems have two 1GbE ethernet ports. Most also have two additional10GbE ports. Network bonding is supported on pairs of 1GbE and 10GbE ports, as describedin the next section.

Network bonding modesEach pair of network ports on the appliance can be configured either on separate subnets or in abond with each other (1GbE and 10GbE ports cannot be bonded together).From software release 3.6.x onwards three bonding modes are supported:• Mode 1 (Active/Backup)

This is the most simple bonding mode; it allows network traffic via one active port only andrequires no specific extra switch configuration. It is recommended for simple networkconnections.

• Mode 4 (IEEE 802.3ad Dynamic Link Aggregation)This bonding mode is also known as LACP and requires a special external switch configuration.It provides a link aggregation solution, increasing the bond physical bandwidth but can onlywork if all the ports in the bond are connected to one switch. It is recommended when :

◦ The customer wants to increase throughput to the StoreOnce appliance

◦ Trunks between switches on the customer network already use LACP mode

The LACP protocol only works when it is configured on both ends of the physical connection.

• Mode 6 (Active Load Balancing)This mode provides a load balance solution. It does not require specific external switchconfiguration, but does require the switch to allow ARP negotiation. It can be used in a 2–switchconfiguration.

Network configuration in single-node StoreOnce Backup systemsNOTE: Please refer to the HP StoreOnce 2700, 4500 and 4700 Backup system Installation andconfiguration guide or HP StoreOnce 2620, 4210/4220 and 4420/4430 Backup systemInstallation and configuration guide for detailed information about installing the StoreOnce Backupsystem and configuring it on a network. It contains information about the network wizard andnetwork configuration files that is not included in this guide.

This section explains network configurations for the following single-node Backup systems, whichare installed and configured by the customer:

• HP StoreOnce 2700




• HP StoreOnce 4210/4220

• HP StoreOnce 4420/4430The multi-node StoreOnce B6200 Backup system has additional networking considerations, whichare described separately in the next section of this chapter. Installation and configuration of thesesystems is normally carried out by HP service specialists.

28 Networking considerations

General guidelinesSingle node StoreOnce appliances have a factory default network configuration where the first1GbE port (Port 1 /eth0) is enabled in DHCP mode. This enables quick access to the StoreOnceCLI and Management GUI for customers using networks with DHCP servers and DNS lookupbecause the appliance hostname is printed on a label on the appliance itself. The default bondingmode is Mode 1.Mode 6 bonding provides port failover and load balancing across the physical ports. There is noneed for any network switch configuration in this mode. This network bonding mode requires thatthe same switch is used for each network port or that spanning tree protocol is enabled, if separateswitches are used for each port.If external switch ports are configured for LACP (Mode 4) bonding and Mode 6 bonding is required,then LACP must be un-configured.Network configuration on StoreOnce Backup systems is performed via the CLI Managementinterface.For detailed information about configuring network bonding modes, please refer to the HPStoreOnce 2620, 4210/4220 and 4420/4430 Backup system Installation and Configurationguide.

Network configuration in single-node StoreOnce Backup systems 29

Single port configurationsThe example shows the simplest configuration of a single subnet containing just one 1GbE networkport, generally this configuration is likely to be used:

• Only if the network interface is required only for management of the appliance or

• Only if low performance and resiliency backup and restore are acceptable.A single 10GbE port could also be configured in this way (on 4420/4430 appliances), providingboth a backup data interface and management interface. This could deliver good performance,however, bonded ports are recommended for resiliency and maximum performance.

Figure 10 Network configuration, single port mode


Dual port configurationsThis example describes configuring multiple subnets in separate IP address ranges for each pairof network ports. A maximum of 4 separate subnets can be configured on a StoreOnce 4420 or4430 appliance (2 x 1GbE and 2 x 10GbE).Use this mode:

• If servers to be backed up are split across two physical networks which need independentaccess to the appliance. In this case, virtual libraries and shares and Catalyst stores will beavailable on both network ports; the host configuration defines which port is used.

• If separate data (“Network SAN”) and management LANs are being used, i.e. each serverhas a port for business network traffic and another for data backup. In this case, one port onthe appliance can be used solely for access to the StoreOnce Management Interface with theother used for data transfer.

Figure 11 Network configuration, dual port mode

In the case of a separate network SAN being used, configuration of CIFS backup shares withActive Directory authentication requires careful consideration, see Network Configurations for CIFSAD for more information.


Bonded port configurations (recommended)If two network ports are configured within the same subnet they will be presented on a single IPaddress and will be bonded using one of the bonding modes as described in Network bondingmodes.This configuration is generally recommended for backup data performance and also for resiliencyof both data and management network connectivity. It should be noted that when using bondedports the full performance of both links will only be realized if multiple host servers are providingdata, otherwise data will still use only one network path from the single server.

Figure 12 Network configuration, bonded


10GbE Ethernet ports on StoreOnce Backup systems10GbE Ethernet is provided as a viable alternative to the Fibre Channel interface for providingmaximum iSCSI VTL performance and also comparable NAS performance. 10GbE ports alsoprovide good performance when using StoreOnce Catalyst low and high bandwidth backup aswell as Catalyst copy or VTL/NAS replication between appliances. When using 10GbE Ethernetit is common to configure a “Network SAN”, which is a dedicated network for backup that isseparate to the normal business data network; only backup data is transmitted over this network.

Figure 13 Network configuration with 10GbE ports

As well as CIFS and NFS shares the devices configured could equally be Catalyst stores.When a separate network SAN is used, configuration of CIFS backup shares with Active Directoryauthentication requires careful consideration, see the next section for more information.

Network configuration for CIFS ADWhen using CIFS shares for backup on a StoreOnce device in a Microsoft Active Directoryenvironment the appliance CIFS server may be made a member of the AD Domain so that ActiveDirectory users can be authenticated against CIFS shares on the StoreOnce Backup system.However, in order to make this possible the AD Domain controller must be accessible from theStoreOnce device. Broadly there are two possible configurations which allow both:

• Access to the Active Directory server for AD authentication and

• Separation of Corporate LAN and Network SAN traffic


Option 1: HP StoreOnce Backup system on Corporate SAN and Network SANIn this option, the StoreOnce device has a port in the Corporate SAN which has access to theActive Directory Domain Controller. This link is then used to authenticate CIFS share access.The port(s) on the Network SAN are used to transfer the actual data.This configuration is relatively simple to configure:

• On StoreOnce devices with only 1GbE ports: Two subnets should be configured with one portin each. The ports are connected and configured for either the Corporate LAN or NetworkSAN. In this case one data port is “lost” for authentication traffic, so this solution will notprovide optimal performance.

• On StoreOnce devices with both 10GbE and 1GbE ports: the 10GbE ports can be configuredin a bonded network mode and configured for access to the Network SAN. One or both ofthe 1GbE ports can then be connected to the Corporate LAN for authentication traffic. In thiscase optimal performance can be maintained – see below.

The backup application media server also needs network connections into both the Corporate LANand Network SAN.

Figure 14 HP StoreOnce Backup system on Corporate SAN and Network SAN


Option 2: HP StoreOnce Backup system on Network SAN only with GatewayIn this option the StoreOnce appliance has connections only to the Network SAN, but there is anetwork router or Gateway server providing access to the Active Directory domain controller onthe Corporate LAN. In order to ensure two-way communication between the Network SAN andCorporate LAN the subnet of the Network SAN should be a subnet of the Corporate LAN subnet.Once configured, authentication traffic for CIFS shares will be routed to the AD controller but datatraffic from media servers with a connection to both networks will travel only on the Network SAN.This configuration allows both 1GbE network connections to be used for data transfer but alsoallows authentication with the Active Directory Domain controller. The illustration shows a simpleClass C network for a medium-sized LAN configuration.

Figure 15 HP StoreOnce Backup system on Network SAN only with Gateway


5 Network configuration in multi-node StoreOnce Backupsystems

The multi-node StoreOnce B6200 Backup system has specific networking considerations to ensuresupport for autonomic failover. Installation and configuration of these systems is normally carriedout by HP service specialists. Before installation the customer is asked to read the HP StoreOnceB6000 Series Backup system Installation Planning and Preparation Guide and complete the checklistthat specifies the information that the engineer needs to configure the system.Each couplet is a paired combination of two nodes that are directly connected in failover pairs. Ifone node fails, the system is designed to failover to the other node without any external interactionfrom the customer. The B6200 Series Backup system uses a concept called a Virtual NetworkInterface (VIF) to make this possible.In very simple terms:

• The physical IP addresses relate to the physical ports that are used to connect the HP B6200Backup system to the customer's network

• The Virtual Network Interface (VIF) addresses are the IP addresses that the customer uses toconnect to the B6200 Management Console (GUI and CLI) and to target backup and replicationjobs. Because these are never directly linked to a physical port they continue to functioncorrectly in the event of node failure.

For a more detailed discussion of how VIFs and IP addresses are used see the HP StoreOnceBackup system installation preparation and planning guide.

What is currently supported• IPv4 is supported.

• DNS is supported.

• A maximum of two sub-nets is supported, which can be used as follows: one sub-net for data(NAS shares, Catalyst stores and replication) and one sub-net for management.

• For software revision 3.3.0 and greater up to two gateways are supported. If you wish toconfigure two sub-nets with only one external gateway, make sure that the gateway is on thesame sub-net as the network that requires access to remote sites.

• Three network bonding modes are supported, as described in Network bonding modes.

• NAS shares, Catalyst stores and replication data use the same Ethernet channel.

• If you wish to use your Ethernet channel for replication only, the only supported backup optionis to create VTL libraries on Fibre Channel.

• The network configuration applies to all nodes in the cluster. For example, you cannot haveseparate network configurations for each rack in a two-rack system.

What is not currently supported• IPv6 is not supported.

• DHCP is not supported.

• There is no VTL support on Ethernet using the iSCSI protocol.

Supported network configurations (templates)Network ports are bonded to ensure high availability. (But there is no network bonding between1Gb and 10Gb ports.)

36 Network configuration in multi-node StoreOnce Backup systems

The optimum configuration is to use the 10GbE ports for data (NAS shares and Catalyst stores)and all replication traffic, and the 1GbE ports for the B6000 Management Console. However, thisrequires two sub-nets and may not be available to all users.Five network configurations are supported and configured using one of the supplied networktemplates, illustrated on the following pages. You must decide which template you intend to useprior to installation.

Gateway considerationsWhen the network is configured, you are prompted to provide an IP address for a default gateway,which will be used to route management and data traffic to and from an external network. Twoof the templates support customer sites with two sub-nets and allow you to route data traffic on onenetwork and management on the second. For software revision 3.3.0 and greater, for thesetemplates you are given the opportunity to provide the IP address of a second gateway and specifywhich type of traffic it should take.There are up to three choices when configuring the network (using the StoreOnce CLI):

• No external gateways: If the customer wants to use the HP StoreOnce B6200 Backup Systemin a totally isolated network environment, they should not configure an external gateway (theHP support engineer will simply skip this step during configuration)

• One external gateway: This is the standard configuration with templates 2, 3 and 5, wheredata and management traffic are routed to the same subnet, so only one external gateway isrequired. When used with templates 1 and 4, the customer must select which subnet (data ormanagement) will have the ability to communicate with the external gateway.

• Two external gateways (applies to templates 1 and 4 only and for software revision 3.3.0and greater): This configuration allows both management and data subnets to communicatewith the external network. The IP addresses of the two gateways are provided during thenetwork configuration. The customer must select whether data or management traffic will usethe 'default' gateway.

NOTE: In this context, 'default' is purely a mechanism to allow the user to specify a gateway forone type of traffic; the second gateway is automatically used for the other type of traffic.

Examples

• Customer has a 10GbE and a 1GbE network and only wants data to be accessible remotely:Use Template 1, but configure one gateway only to the 10GbE network for data

• Customer has a 10GbE and a 1GbE network and wants both data and management to beaccessible remotely: Use Template 1 and configure two gateways. Decide whether data ormanagement should use the 'default' gateway.

• Customer has a 10GbE or a 1GbE network only and wants data and management to beaccessible remotely: Use Template 2, 3 or 4, as appropriate and configure one gateway.

• Customer has a 10GbE or a 1GbE network only and does not want data or management tobe accessible remotely: Use Template 2, 3 or 4, as appropriate and do not configure agateway.

NOTE: For software revision 3.3.0 and greater: if the customer wants to have only two 1GbEnetwork connection from each node in a couplet to their Ethernet switches, they should use Template5 instead of Template 2 in the above examples.

Template 1, uses 10 GbE and 1 GbE sub-netsTemplate 1 supports users who have a 10GbE network and a 1GbE network and wish to useseparate sub-nets for data and management. The gateway must be in the same sub-net as thenetwork that is being used to connect to remote sites. This is normally the data path network.

Supported network configurations (templates) 37

The default bonding mode for this template is Mode 1, Active/Backup, on both sub-nets.The recommended IP address range is 25 in total: 16 contiguous on the data sub-net; 1 + 8contiguous on the management sub-net.

NOTE: When using a 10GbE network, you must provide the correct SFPs for your environment.They are not supplied with the product.

Figure 16 Template 1 cabling to customer's networks

bonded 10 GbE ports, normally to customer's data sub-net1 and 2

bonded 1 GbE ports, normally to customer's management sub-net3 and 4

internal cabling, should not be removedblue cables


Template 2, uses 1GbE network onlyTemplate 2 supports users who have a 1GbE network only. The same network is used for dataand management.The default bonding mode for this template is Mode 6, Active Load Balancing.The recommended IP address range is 17 in total: 1 for management and 16 contiguous for data.

NOTE: For software revision 3.3.0 and greater: customers who do not have a sufficient numberof physical Ethernet ports to support Template 2 should use Template 5 instead.


bonded 1 GbE ports to customer's data and management network1, 2, 3 and 4



Template 3, uses 10GbE network onlyTemplate 3 supports users who have a 10GbE network only. The same network is used for dataand management.The default bonding mode for this template is Mode 1, Active/Backup.The recommended IP address range is 17 in total: 1 for management and 16 contiguous for data.

NOTE: When using a 10GbE network, you must provide the correct SFPs for your environment.They are not supplied with the product.


bonded 10 GbE ports to customer's data and management network1 and 2


Template 4, uses two 1GbE networksTemplate 4 supports users who have two 1GbE networks. One 1 GbE network is used for data;the other is used for management. The gateway must be in the same sub-net as the network thatis being used to connect to remote sites. This is normally the data path sub-net, for example usedfor remote/external site replication traffic.The default bonding mode for this template is Mode 1, Active/Backup, on both sub-nets.The recommended IP address range is 25 in total: 16 contiguous on the data sub-net; 1 + 8contiguous on the management sub-net.


bonded 1 GbE ports to customer's management sub-net1 and 3

bonded 1 GbE ports to customer's data sub-net2 and 4

internal cabling, should not be removedlight blue cables

Supported network configurations (templates) 39

Template 5, uses 1GbE network onlyFor software revision 3.3.0 and greater: Template 5 supports users who want to have only two1GbE network connections from each node in a couplet to their Ethernet switches. The same networkis used for data and management. It is primarily for customers who only use VTL as their backuptargets and do not use StoreOnce Catalyst stores or NAS CIFS/NFS shares. VTL replication jobswill still run over the Ethernet connections.The default bonding mode for this template is Mode 1, Active/Backup, on both sub-nets.The recommended IP address range is 17 in total: 1 for management and 16 contiguous for data.


bonded 1 GbE ports to customer's data and management network1 and 3

not used2 and 4



6 Fibre Channel considerationsThe HP StoreOnce B6200 Backup system supports switched fabric using NPIV only. All other HPStoreOnce Backup systems support both switched fabric and direct attach (private loop) topologies.Switched fabric using NPIV (N Port ID Virtualisation) offers a number of advantages and is thepreferred topology for all StoreOnce appliances.

NOTE: As with networking the multi-node StoreOnce B6200 Backup system has specific FCconsiderations to ensure support for autonomic failover. This chapter contains generic informationabout FC support. See also Configuring FC to support failover with the HP StoreOnce B6200Backup system (page 47).

• Virtual library devices are assigned to an individual interface. Therefore, for best performance,configure both FC ports and balance the virtual devices across both interfaces to ensure thatone link is not saturated whilst the other is idle.

• Switched fabric mode is preferred for optimal performance on medium to large SANs sincezoning can be used. Switched fabric mode is required for the HP B6200 Backup system.

• Use zoning (by Worldwide Name) to ensure high availability.

• When using switched fabric mode, Fibre Channel devices should be zoned on the switch tobe only accessible from a single backup server device. This ensures that other SAN events,such as the addition and removal of other FC devices, do not cause unnecessary traffic to besent to devices. It also ensures that SAN polling applications cannot reduce the performanceof individual devices.

• Either or both of the two FC ports may be connected to a FC fabric and each virtual librarymay be associated with one or both of these FC ports but each drive can only be associatedwith one port. Port 1 and 2 is the recommended option in the GUI to achieve efficient loadbalancing. Only the robotics (medium changer) part of the VTL is presented to Port 1 and Port2 initially, with the number of virtual tape drives defined being presented 50% to Port 1 and50% to Port 2. This also ensures that in the event of a fabric failure at least half of the driveswill still be available to the hosts. (The initial virtual tape drive allocation to ports (50/50) canbe edited later, if required.

Port assignment for StoreOnce Backup systems with two Fibre Channelcards

StoreOnce B6200, 4900 and 4700 model only: These models have two FC cards per server; thereare four FC ports (B6200: available on each node). When creating a library you may selectindividual drives or FC ports 1&2 or FC ports 3&4. Be aware that Port 1 and port 3 are on thefirst FC card; port 2 and port 4 are on the second FC card, so it is important to ensure that thesystem has been cabled correctly when connecting to the FC SAN. If you select one of the combinedport options, both FC cards must be connected.Drives can only appear on one port, so when you choose a pair of ports, drives are automaticallydistributed evenly across both ports to ensure best performance and failover. After creating thelibrary, it is possible to change the drive assignments using the edit function on the InterfaceInformation tab for the selected library.

Port assignment for StoreOnce Backup systems with two Fibre Channel cards 41

General Fibre Channel configuration guidelinesNOTE: The illustrations in this section show single node products (HP StoreOnce 4500, 4700,4210 and 4220, and 4420 and 4430). Additional configuration requirements apply with the HPStoreOnce B6200 Backup system to support autonomic failover. For examples that illustrate multinode products (HP StoreOnce B6200) see Configuring FC to support failover with the HP StoreOnceB6200 Backup system.

Switched fabricA switched fabric topology utilizes one or more fabric switches configured in one or more storagearea networks (SANs) to provide a flexible configuration between several Fibre Channel hosts andFibre Channel targets such as the StoreOnce appliance virtual libraries. Switches may be cascadedor meshed together to form large fabrics.

Figure 21 Fibre Channel, switched fabric topology

StoreOnce does not implement any selective virtual device presentation, and so each virtual librarywill be visible to all hosts connected to the same fabric. It is recommended that each virtual libraryis zoned to be visible to only the hosts that require access. Unlike the iSCSI virtual libraries, FCvirtual libraries can be configured to be used by multiple hosts, if required.

42 Fibre Channel considerations

The illustration above shows the flexibility of the configuration

• VTL1 is connected to FC Port 1 exclusively

• VTL3 is connected to FC Port 2 exclusively

• VTL2 is spread across FC Port 1 and FC Port 2. The medium changer is connected to bothports whereas the drives by default are connected 50% to each port (2 each in this case).This mode is useful in high availability SANs

General Fibre Channel configuration guidelines 43

Direct Attach (private loop)A direct attach (private loop) topology is implemented by connecting the StoreOnce applianceports directly to a Host Bus Adapter (HBA). In this configuration the Fibre Channel private loopprotocol must be used.

NOTE: The HP StoreOnce B6200 Backup system is not supported in direct attach configurations.

Figure 22 Fibre Channel, direct attach (private loop) topology

Either of the FC ports on a StoreOnce Backup system may be connected to a FC private loop,direct attach topology. The FC port configuration of the StoreOnce appliance should be changedfrom the default N_Port topology setting to Loop. This topology only supports a single host connectedto each private loop configured FC port. In Private loop mode the medium changer cannot beshared across FC Port 1 and FC port 2.

ZoningZoning is only required if a switched fabric topology is used and provides a way to ensure thatonly the hosts and targets that they need are visible to servers, disk arrays, and tape libraries.Some of the benefits of zoning include:

• Limiting unnecessary discoveries on the StoreOnce appliance

• Reducing stress on the StoreOnce appliance and its library devices by polling agents

• Reducing the time it takes to debug and resolve anomalies in the backup/restore environment

• Reducing the potential for conflict with untested third-party products

• Zoning implemention needs to ensure StoreOnce FC diagnostic device is not presented tohosts


Zoning may not always be required for configurations that are already small or simple. Typicallythe larger the SAN, the more zoning is needed. Use the following guidelines to determine howand when to use zoning.

• Small fabric (16 ports or less)—may not need zoning

• Small to medium fabric (16 - 128 ports)—use host-centric zoning. Host-centric zoning isimplemented by creating a specific zone for each server or host, and adding only those storageelements to be utilized by that host. Host-centric zoning prevents a server from detecting anyother devices on the SAN or including other servers, and it simplifies the device discoveryprocess.

• Disk and tape on the same pair of HBAs is supported along with the coexistence of arraymultipath software (no multipath to tape or library devices on the HP StoreOnce Backup system,but coexistence of the multipath software and tape devices).

• Large fabric (128 ports or more)—use host-centric zoning and split disk and tape targets.Splitting disk and tape targets into separate zones will help to keep the HP StoreOnce Backupsystem free from discovering disk controllers that it does not need. For optimal performance,where practical, dedicate HBAs for disk and tape.

Use soft zoning for high availabilityThe StoreOnce appliance allows the robot and tape drives to be presented to the different FC portsthat are connected to the customer’s fabric. The diagram below shows a way of utilizing this featureto add higher availability to your StoreOnce VTL deployment. When the VTL is created there is theoption to present the device to Port1, Port2 or Port 1&2. If the customer chooses to present the VTLto Port 1 &2, the following happens. The robot is presented to both Port1 and Port2, 50% of theconfigured drives are presented to Port1 and the other 50% to Port2 (this can be changed ifrequired). With this configuration in the event of a Fabric Failure – the robot and 50% of the drivesare available for backup. The downside to this feature is that only a single 8Gb FC link is availablefor backups.

Figure 23 VTL Fibre Channel resiliency using WWN zoning

General Fibre Channel configuration guidelines 45

Use the StoreOnce Management GUI to find out the WWPN for use in zoning. The WW portnames are on the VTL-Libraries-Interface Information tab.

Diagnostic Fibre Channel devicesFor each StoreOnce FC port there is a Diagnostic Fibre Channel Device presented to the Fabric.There will be one per active FC physical port. This means there are two per HP StoreOnce Backupsystem or node that has two Fibre Channel ports.The Diagnostic Fibre Channel Device can be identified by the following example text (taken froma single node system).Symbolic Port Name "HP D2D S/N-CZJ1440JBS HP D2DBS Diagnostic Fibre Channel S/N-MY5040204H Port-1"Symbolic Node Name "HP D2D S/N-CZJ1440JBS HP D2DBS Diagnostic Fibre Channel S/N-MY5040204H"

A virtual driver or loader would be identified by the following example text:Symbolic Port Name "HP D2D S/N-CZJ1440JBS HP Ultrium 4-SCSI Fibre Channel S/N-CZJ1440JC5 Port-0"Symbolic Node Name "HP S/N-CZJ1440JBS HP Ultrium 4-SCSI Fibre Channel S/N-CZJ1440JC5"

In the above the S/N-CZJ1440JBS for all devices should be identical. If this is Node Port 1, theNode Name string will be as above but, if Port 2, the Node Name string will end with “Port-2”.Often the diagnostic device will be listed above the other virtual devices as it logs in first aheadof the virtual devices. The S/N-MY5040204H string is an indication of the QLC HBA’s SN notany SN of an appliance/node.At this time these devices are part of the StoreOnce VTL implementation and are not an error orfault condition. It is imperative that these devices be removed from the switch zone that is alsoused for virtual drives and loaders to avoid data being sent to diagnostic devices.


7 Configuring FC to support failover in a StoreOnce B6200Backup system environment

Autonomic failoverAutonomic failover is a unique enterprise class feature of the HP B6200 StoreOnce Backup system.When integrated with various backup applications it makes it possible for the backup process tocontinue even if a node within a B6200 couplet fails. ISV scripts are usually required to completethis process. The failover process is best visualized by watching the video on: http://www.youtube.com/watch?v=p9A3Ql1-BBs

What happens during autonomic failover?At a logical level, all the virtual devices (VTL, NAS and replication) associated with the failingnode are transferred by the B6200 operating system onto the paired healthy node of the couplet.The use of Virtual IP addresses for Ethernet and NPIV virtualization on the Fibre Channel ports arethe key technology enablers that allow this to happen without manual intervention.

• NAS target failover is via the Virtual IP system used in the HP B6200 Backup System – theservice set simply presents the failed node Virtual IP address on the remaining node.

• FC (VTL device) failover relies on the customer’s fabric switches supporting NPIV, and NPIVbeing enabled and the zones set up correctly. Here the situation is more complex as severalpermutations are possible.

NOTE: To prevent data corruption, the system must confirm that the failing node is shutdownbefore the other node starts writing to disk. This can be seen in the video where the “service set”is stopping. At a hardware level the active cluster manager is sending a shutdown command viathe dedicated iLO3 port on the failing node. Email alerts and SNMP traps are also sent on nodefailure.

The HP B6200 Backup System failover process can take 15 minutes or more to complete. The totaltime for failover is dependent on the system integrity checks, which are an integral part of thefailover process, and the need to validate the deduplicated data stored.The following figureillustrates the failover timeline.

Figure 24 Failover timeline

Autonomic failover 47

http://www.youtube.com/watch?v=p9A3Ql1-BBs

http://www.youtube.com/watch?v=p9A3Ql1-BBs

Failover support with backup applicationsBackup applications do not have an awareness of advanced features such as autonomic failoverbecause they are designed for use with physical tape libraries and NAS storage. From theperspective of the backup application, when failover occurs, the virtual tape libraries and the NASshares on the HP B6200 Backup System go offline and after a period of time they come backonline again. This is similar to a scenario where the backup device has been powered off andpowered on again.Each backup application deals with backup devices going offline differently. In some cases, oncea backup device goes offline the backup application will keep retrying until the target backupdevice comes back online and the backup job can be completed. In other cases, once a backupdevice goes offline it must be brought back online again manually within the backup applicationbefore it can be used to retry the failed backups.In this section we shall briefly describe three popular backup applications and their integrationwith the autonomic failover feature. Information for additional backup applications will be publishedon the B6200 support documentation pages when it is available.

• HP Data Protector 6.21: job retries are currently supported by using a post-exec script.Download from B6200 support documentation.

• Symantec NetBackup 7.x: job retries are automatic, but after a period without a responsefrom the backup device the software marks the devices as “down”. Once failover has completedand the backup device is responding again the software does not automatically mark thedevice as “up” again. A script is available from HP that continually checks Symantec devicestatus and ensures that backup devices are marked as “up”. With this script deployed on theNetBackup media server, the HP B6200 Backup System failover works seamlessly. Downloadfrom B6200 support documentation. NetBackup can go back to the last checkpoint and carryon from there, if checkpointing has been enabled in the backup job. So, all the data backedup prior to failover is preserved and the job does not have to go right back to the beginningand start again.

• EMC Networker 7.x:nl

VTL: Job retries are automatically enabled for scheduled backup jobs. No additional scriptsor configuration are required in order to achieve seamless integration with the HP B6200Backup System. In the event of a failover scenario, the backup jobs are automatically retriedonce the HP B6200 Backup System has completed the failover process. EMC Networker alsohas a checkpoint facility that can be enabled. This allows failed backup jobs to be restartedfrom the most recent checkpoint.nl

NAS: The combination of Networker and NAS is not supported with autonomic failover anduse could cause irrecoverable data loss.

It is strongly recommended that all backup jobs to all nodes be configured to restart (if any actionto do this is required) because there is no guarantee which nodes are more likely to fail than others.It is best to cover all eventualities by ensuring all backups to all nodes have restart capabilityenabled, if required.Whilst the failover process is autonomic, the failback process is manual because the replacementor repaired node must be brought back on line before failback can happen. Failback can beimplemented either from the CLI or the GUI interface.Restores are generally a manual process and restore jobs are typically not automatically retriedbecause they are rarely scheduled.

48 Configuring FC to support failover in a StoreOnce B6200 Backup system environment

Designing for failoverOne node is effectively doing the work of two nodes in the failed over condition. There is someperformance degradation but the backup jobs will continue after the autonomic failover. Thefollowing best practices apply when designing for autonomic failover support:

• The customer must choose whether SLAs will remain the same after failover as they did beforefailover. If they do, the solution must be sized in advance to only use up to 50% of the availableperformance. This is to ensure that there is sufficient headroom in system resources so that inthe case of failover there is no appreciable degradation in performance after failover and theSLAs are still met

• For customers who are more price-conscious and where failover is an “exception condition”the solution can be sized for cost effectiveness. Here most of the available throughput is utilizedon the nodes. In this case when failover happens there will be a degradation in performance.The amount of degradation observed will depend on the relative “imbalance” of throughputrequirements between the two nodes. This is another reason for keeping both nodes in acouplet as evenly loaded as possible.

• Ensure the correct ISV patches/scripts are applied and do a dry run to test the solution. Insome cases a post execution script must be added to each and every backup job/policy. Thecustomer can configure which jobs will retry in the event of failover (which is a temporarycondition) in order to limit the load on the single remaining node in the couplet by:

◦ Only putting the post execution script to retry the job in the most urgent and importantjobs, not all jobs. This is the method for HP Data Protector.

◦ Modifying the “bring device back on line scripts” to only apply to certain drives androbots – those used by the most urgent and important jobs. This is the method for SymantecNetBackup.

• Remember replication is also considered as a virtual device within a service set and replicationfails over as well as backup devices

• For replication failover there are two scenarios:

Replication was not running – that is, failover occurred outside the replication window,in which case replication will start when the replication windows is next open.

◦

◦ If replication was in progress when failover occurred, after failover has completedreplication will start again from the last known good checkpoint (about every 10MB ofreplicated data).

• Failback (via CLI or GUI) is a manual process and should be scheduled to occur during aperiod of inactivity.

• Remember all failover related events are recorded in the Event Logs.

Key Failover FC zoning considerationsThe same considerations apply when configuring Fibre Channel as did when configuring thenetwork. Care must be taken to ensure there is no single point of failure in switch or fabric zoningthat will negate the failover capabilities of the HP B6200 Backup System and its autonomic failoverability.Conformance to the following rules will help to ensure successful failover

• Fibre Channel switches used with HP StoreOnce must support NPIV. For a full list see:nl

http://www.hp.com/go/ebs.• Use WWPN zoning (rather than port based).

• In a single fabric configuration ensure the equivalent FC ports from each B6200 node in acouplet are presented to the same FC switch, see Scenario 1.

Key Failover FC zoning considerations 49


• In a dual fabric configuration ensure the equivalent FC ports from each B6200 node in acouplet are presented to the same fabric. However, they should present to separate switcheswithin the fabric. See Scenario 3.

• Ensure the D2D diagnostic device WWNs (these will be seen in the switch name server andare associated with the physical ports) are not included in any fabric zones and, therefore,not presented to any hosts.

Fibre channel port presentationsWhen you create a virtual tape library on a service set you specify whether the VTL should bepresented to:

• Port 1 and 2

• Port 3 and 4

• Port 1

• Port 2

• Port 3

• Port 4Port 1 and 2 (or Port 3 and 4) is the recommended option to achieve efficient load balancing.Only the robotics (medium changer) part of the VTL is presented to Port 1 and Port 2 initially, withthe number of virtual tape drives defined, being presented 50% to Port 1 and 50% to Port 2. Thisalso ensures that in the event of a fabric failure at least half of the drives will still be available tothe hosts. (The initial virtual tape drive allocation to ports (50/50) can be edited later, if required.So, to create a library you need:

• 1 WWN for the robotics

• XX number of WWNs for your drives, depending on the required number of drivesAlthough the universal configuration rule is a maximum of 255 WWNs per port, the HP B6200Backup System applies a maximum of 120 WWNs per port and up to 192 drives per library. Thisis to ensure fabric redundancy and to enable failover to work correctly. For example, should Port1 fail in any of the selected configurations, the WWNs associated with its service set will notexceed 120 and can be failed over safely to Port 2.To summarize:

• To create a library on one port only, the maximum number of devices that you can have is120, of which 1 WWN is required for the robotics, so the total number of drives available= 119 drives

• To create a library on Ports 1 and 2 (or Ports 3 and 4), the maximum number of drives is 96per port (but this configuration is not recommended). This is a B6200 library limit and not aWWN limit.

The following table illustrates various FC port configurations with VTL devices and the impact thatthe choice of FC ports has on the validity of the configuration.

NOTE: This table will be updated to include Ports 3 and 4 in the next version of this guide.


Figure 25 VTL FC example port configurations

Fibre channel port presentations 51

Scenario 1, single fabric with dual switches, recommendedFigure 40 illustrates the logical connectivity between the hosts and the VTLs and their FC ports. Thearrows illustrate accessibility, not data flow.FC configuration

• Multiple switches within a single fabric

• All hosts can see the robots over two separate switches

• Zoning by WWPN

• Each zone to include a host and the required targets on the HP B6200 Backup System

• Equivalent ports from each node can see the same switchB6200 VTL configuration

• Default library configuration is 50% drives presented to Port 1, 50% presented to Port 2

• Up to 120 WWNs can be presented to Port 1 and Port 2

• On B6200 failover all WWNs of failed node are automatically transferred to the correspondingport on the other node. This is transparent to the hosts.

Figure 26 VTLs presented to two ports and into dual switches in a single Fabric, recommendedconfiguration


If FC switch1 fails, Host A and Host B lose access to their backup devices. Hosts C and D still haveaccess to the media changers and to 50% of the drives on VTL2 and 50% of the drives on VTL1B6200 failover between nodes is enabled.

Scenario 2, single fabric with dual switches, not advisedThe FC configuration is the same in this scenario, but the VTLs are presented to a single port. Thisconfiguration is not advised because it compromises the B6200 autonomic failover facility.FC configuration

• Multiple switches within a single fabric

• All hosts can see the robots over two separate switches

• Zoning by WWPN

• Each zone to include a host and the required targets on the HP B6200 Backup system

• Equivalent ports on each node see different switchesB6200 VTL configuration

• B6200 failover nodes will not failover if we lose a FC port on the node

• Up to 120 WWNs can be presented to the individual port

• Loss of a port or switch means that all access is lost to the VTLs that are dedicated to that port

• Library configuration is all drives presented entirely to a single port, either Port 1 or Port 2

Figure 27 Separate VTLs presented to separate ports and into different switches in different Fabrics,not recommended

Scenario 2, single fabric with dual switches, not advised 53

If FC switch1 fails, Host A and Host B lose access to their backup devices, even though B6200failover is enabled because the physical configuration provides a point of failure. Hosts C and Dstill have access to the media changers and to 100% of the drives on VTL3 and VTL4.

Scenario 3, dual fabric with dual switches, recommendedThis FC configuration has added complexity because it has two fabrics. The arrows illustrateaccessibility, not data flow.FC configuration

• Dual fabrics

• Multiple switches within each fabric

• Zoning by WWPN


• Equivalent ports from each node can see the same fabric, but are directed to different switchesB6200 VTL configuration

• Default library configuration is 50% drives presented to Port 1, 50% presented to Port 2. Robotappears on Port 1 and Port 2

• Up to 120 WWNs can be presented to Port 1 and Port 2

• On B6200 failover all WWNs of failed node are automatically transferred to the correspondingport on the other node, which still has access to both fabrics. This is transparent to the hosts.

Figure 28 Complex configuration with ports of different VTLs being presented to different fabrics,recommended configuration


What happens if a fabric fails?If Fabric 1 fails in the previous configuration, all VTL libraries and nodes on the HP B6200 BackupSystem still have access to Fabric 2. As long as Hosts A, B and C also have access to Fabric 2,then all backup devices are still available to Hosts A, B and C. The following diagram illustratesexisting good paths after a fabric fails.

Figure 29 Complex configuration with ports of different VTLs being presented to different fabrics,Fabric 1 fails

Similarly, if Fabric 2 failed, all VTL libraries and nodes on the HP B6200 Backup System wouldstill have access to Fabric 1. As long as Hosts D, E and F also have access to Fabric 1, then allbackup devices are still available to Hosts D, E and F. The following diagram illustrates goodexisting paths after Fabric 2 fails.

Scenario 3, dual fabric with dual switches, recommended 55

Figure 30 Complex configuration with ports of different VTLs being presented to different fabrics,Fabric 2 fails

Scenario 4, dual fabric with dual switches, not advisedThe FC configuration is the same as scenario 3, but the VTLs are presented to a single port, whichmeans they are tied to a single switch within a single fabric. This configuration is not advisedbecause it compromises the B6200 autonomic failover facility.FC configuration

• Dual fabrics

• Multiple switches within each fabric

• Zoning by WWPN


• Equivalent ports from each node are connected to the same fabric, but are directed to differentswitches

• Each port is connected to only one switch within one fabricB6200 VTL configuration

• Library configuration is all drives presented entirely to a single port, either Port 1 or Port 2.

• Loss of a port, switch or fabric means that all access is lost to the VTLs that are dedicated tothat port, switch or fabric


Figure 31 Complex configuration with ports of different VTLs being presented to different fabrics,not advised

Scenario 4, dual fabric with dual switches, not advised 57

8 StoreOnce Catalyst storesStoreOnce Catalyst technology

HP StoreOnce Catalyst delivers a single, integrated, enterprise-wide deduplication algorithm. Itallows the seamless movement of deduplicated data across the enterprise to other StoreOnceCatalyst systems without rehydration. This means that the user benefits from:

• Simplified management of data movement from the backup application: tighter integrationwith the backup software to manage file replication centrally across the enterprise from thebackup application GUI.

• Seamless control across complex environments: supporting a range of flexible configurationsthat enable the concurrent movement of data from one site to multiple sites, and the ability tocascade data around the enterprise (sometimes referred to as multi-hop).

• Enhanced performance: distributed deduplication processing using StoreOnce Catalyst storeson the StoreOnce Backup system and on multiple servers can optimize network loading andappliance throughput.

• Faster time to backup to meet shrinking backup windows: up to 100 TB/hour* aggregatethroughput, which is up to 4 times faster than backup to a NAS target.

*Actual performance is dependent upon the specific StoreOnce appliance, configuration, dataset type, compression levels, number of data streams, number of devices and number of concurrenttasks, such as housekeeping or replication. All HP StoreOnce Backup systems can support Catalyststores, Virtual Tape libraries and NAS (CIFS/NFS) shares on the same system, which makes themideal for customers who have legacy requirements for VTL and NAS but who wish to move to HPStoreOnce Catalyst technology.HP StoreOnce Catalyst stores require a separate license on both source and target; VTL/NASdevices only require licenses if they are replication targets.

Key featuresThe following are the key points to be aware of with StoreOnce Catalyst:

• Optional deduplication at the backup server enables greater overall StoreOnce applianceperformance and reduced backup bandwidth requirements. This can be controlled at backupsession/job level.

• HP StoreOnce Catalyst enables advanced features such as duplication of backups betweenappliances in a network-efficient manner under control of the backup application.

• Catalyst stores can be copied using low-bandwidth links – just like NAS and VTL devices. Thekey difference here is that there is no need to set up replication mappings (required with VTLand NAS); the whole of the Catalyst copy process is controlled by the backup software itself.

• HP StoreOnce Catalyst enables space occupied by expired backups to be returned for re-usein an automated manner because of close integration with the backup application

• HP StoreOnce Catalyst enables asymmetric expiry of data. For example: retain 2 weeks onthe source, 4 weeks on the target device.

• HP StoreOnce Catalyst store creation can be controlled by the backup application, if required,from within Data Protector (not available with Symantec products).

• StoreOnce Catalyst is fully monitored in the Storage Reporting section of the StoreOnceManagement GUI and StoreOnce Catalyst Copy can be monitored on a global basis by usingHP Replication Manager V2.1 or above.

58 StoreOnce Catalyst stores

• HP StoreOnce Catalyst is an additional licensable feature both on the StoreOnce applianceand within the backup software because of the advanced functionality it delivers.

• HP StoreOnce is only supported on HP Data Protector 7.01, Symantec NetBackup 7.x andSymantec Backup Exec 2012.

StoreOnce interfaces with StoreOnce CatalystThe following diagram shows the basic concept of a StoreOnce Catalyst store; it is a networkbased (not FC based) type of backup target, that exists alongside VTL and NAS targets. The maindifference between a Catalyst store and VTL or NAS devices is that the processor-intensive part ofdeduplication (hashing/chunking and compressing) can be configured to occur on either the mediaserver or the StoreOnce appliance.

• If deduplication is configured to occur on the media server supplying data to the Catalyststore, this is known as low bandwidth backup or source deduplication.

• If deduplication is configured to occur on the StoreOnce appliance where the Catalyst storeis located, this is known as target-side deduplication or high-bandwidth backup. ALL thededuplication takes place on the StoreOnce appliance.

The low bandwidth mode is expected to account for the majority of Catalyst implementations sinceit has the net effect of improving the overall throughput of the StoreOnce appliance whilst reducingbackup bandwidth consumed. It can also be used to allow remote offices to back up directly to acentral StoreOnce Appliance over a WAN link for the first time. Catalyst stores are tolerant of highlatency links – this has been tested by HP. The net effect is the same in both cases – a significantreduction in bandwidth consumed by the data path to the backup storage target.

Figure 32 StoreOnce interfaces with StoreOnce Catalyst

StoreOnce interfaces with StoreOnce Catalyst 59

The deduplication offload into the media server is implemented in different ways in different backupapplications.• With HP Data Protector the StoreOnce deduplication engine is embedded in the HP Data

Protector Media Agent that talks to the Catalyst API.• In Symantec products HP has developed an OpenStorage (OST) Plug-in to NetBackup and

Backup Exec that creates the interface between Symantec products and the StoreOnce Catalyststore API.

Catalyst stores can also be copied using low bandwidth links – just like NAS and VTL devices. Thekey difference here is that there is no need to set up replication mappings (required with VTL andNAS); the whole of the Catalyst copy process is controlled by the backup software itself. This isimplemented by sending “Catalyst Copy” commands to the Catalyst API that exists on the sourceStoreOnce appliance. This simple fact, that the backup application controls the copy process andis aware of all the copies of the data held in Catalyst stores, solves many of the problems involvedin Disaster Recovery scenarios involving replicated copies. No import is necessary because allentries for all copies of data already exist in the backup application’s Database.

Catalyst CopyCatalyst Copy should not be considered in the same way as VTL and NAS replication, since thereis effectively no hard constraints other than capacity on how many Catalyst stores can be copied(replicated) into a Catalyst store at a central site. Furthermore, because Catalyst copies are controlledby the backup application, multi-hop replication is possible using Catalyst devices. However,Catalyst blackout windows can be set on the StoreOnce appliance to dictate when the copy jobactually happens and bandwidth throttling can also be enforced to limit the amount of WAN linkconsumed by StoreOnce Catalyst copy; in this respect it is similar to NAS and VTL replication.Catalyst Copy has the following features:• The Copy job is configurable from within the backup application software.

• Several source Catalyst stores can be copied into a single target Catalyst store.

• Multi-hop copy is configurable via the backup software – Source to Target 1 then onto Target2.

• One to many copy is also configurable but happens serially one after the other.

• With the Catalyst Agents running on remote office media servers HP StoreOnce Catalysttechnology has the ability to back up directly from remote sites to a central site, using whatis known as low bandwidth backup – essentially this uses HP StoreOnce replication technology.


Figure 33 Catalyst copy models

Summary of Catalyst best practicesHP StoreOnce Catalyst is a unique interface and is fundamentally different from virtual tape orNAS. It provides the backup application with full control of backup and replication (called CatalystCopy). For this reason, best practices are dependent upon the backup application. See the separatedocument, HP StoreOnce Backup system Best Practices for VTL, NAS, StoreOnce Catalyst andReplication Implementations with sizing and application configuration examples for more details.Generic best practices for HP StoreOnce Catalyst implementations are:

• Ensure that the media servers where Catalyst low bandwidth backup is to be deployed aresized accordingly; otherwise, the implementation will not work well.

• As with other device types, the best deduplication ratios are achieved when similar data typesare sent to the same device.

• Best throughput is achieved with multiple streams, the actual number per device/appliancevaries by model . Because Catalyst stores can be acting as a backup target and inboundreplication target the maximum value applies to the two target types combined (althoughinbound copy jobs would not normally run at the same time as backups)

• Although Catalyst copy is controlled by the backup software, the copy blackout windowoverrides the backup software scheduling. Check for conflicts.

• The first Catalyst low bandwidth backup will take longer than subsequent low bandwidthbackups because a seeding process has to take place.

• If you are implementing multi-hop or one-to-many Catalyst copies, remember that these copieshappen serially not in parallel.

Summary of Catalyst best practices 61

• Ensure the backup clean-up scripts that regularly check for expired Catalyst Items run at afrequency that avoids using excessive storage to hold expired backups (every 24 hours isrecommended).

• There are several specific tuning parameters dependent on backup application implementation– please see separate document for more details..

StoreOnce Catalyst and the StoreOnce GUIRefer to the HP StoreOnce Backup system user guide or online help for detailed information aboutusing the Catalyst functions on the StoreOnce GUI.

Maximum concurrent jobs and blackout windowsAs with VTL and NAS replication, each StoreOnce appliance supports a maximum number ofconcurrent jobs. In this case, the parameters are Outbound copy jobs and Data and Inbound Copyjobs. Bear in mind that Catalyst stores can act as both inbound and outbound copies when usedin multi-hop mode. See Key parameters (page 115).The concurrency settings for Catalyst are configured by selecting the StoreOnce Catalyst - Settingstab and Edit.

Figure 34 StoreOnce Catalyst settings

Catalyst copy blackout windows are configured from the StoreOnce Catalyst-Blackout Windowstab.

Figure 35 StoreOnce Catalyst blackout windows

The user can also configure bandwidth limiting from the StoreOnce Catalyst-Bandwidth LimitingWindows tab.


Figure 36 StoreOnce Catalyst Bandwidth limiting

Client access permissionsCatalyst stores have a process that allows client access to the Catalyst stores to be controlled.First overall client access permission checking is enabled from the StoreOnce Catalyst – Settingstab.

Figure 37 Enabling client access permission checking

Then each Catalyst store has a list of clients defined who are allowed to access it from the StoreOnceCatalyst – Stores – Permissions tab.

StoreOnce Catalyst and the StoreOnce GUI 63

Figure 38 Setting access permissions for a store

More informationHP StoreOnce Catalyst is a unique interface and is fundamentally different from virtual tape orNAS. It provides the backup application with full control of backup and replication (called CatalystCopy). For this reason, best practices and configuration are dependent upon the backup application.See the separate document, HP StoreOnce Backup systems Best practices for VTL, NAS, StoreOnceCatalyst and Replication implementations with sizing and application configuration examples.


9 Virtual Tape DevicesOverview

Virtual Tape Devices are backup target devices on the HP StoreOnce Backup system to which thebackup application on the hosts write data. They appear to the host as a locally-attached physicaltape library, but physically, they use disk space on the HP StoreOnce Backup system which, as intape terminology, is referred to as slots or cartridges.Tape Libraries provide considerable storage capacity and full support for tape rotation strategies.(It may be necessary to upgrade your backup application to support libraries.)

Tape Library Emulation

Emulation typesHP StoreOnce Backup systems can emulate several types of physical HP Tape Library device; themaximum number of drives and cartridge slots is defined by the type of library configured. Theoptions available vary according to the HP StoreOnce Backup system model.Performance is not related to library emulation other than in the respect of the ability to configuremultiple drives per library and thus enable multiple simultaneous backup streams (multi-streamingoperation).To achieve the best performance of the larger StoreOnce appliances more than one virtual librarywill be required to meet the multi-stream needs. The appliance is provided with a drive pool andthese can be allocated to libraries in a flexible manner and so many drives per library can beconfigured up to a maximum as defined by the library emulation type. The number of cartridgesper library can also be configured. The table below lists the key parameters all StoreOnce products.To achieve best performance the recommended maximum concurrent backup streams per libraryand appliance in the table should be followed. As an example, while it is possible to configure200 drives per library on a 4420 appliance, for best performance no more than 12 of these drivesshould be actively writing or reading at any one time.See also Key parameters (page 115).

NOTE: The maximum number of virtual devices supported varies according to the product andthis number is split across VTL, NAS and Catalyst devices. The table above illustrates maximumconfigurations for libraries and drives, but this number may be limited if you have already createdNAS shares and Catalyst stores.

The HP D2DBS emulation type and the ESL/EML type provide the most flexibility in numbers ofcartridges and drives. This has two main benefits:

• It allows for more concurrent streams on backups which are throttled due to host applicationthroughput, such as multi-streamed backups from a database.

• It allows for a single library (and therefore Deduplication Store) to contain similar data frommore backups, which then increases deduplication ratio.

The D2DBS emulation type has an added benefit in that it is also clearly identified in most backupapplications as a virtual tape library and so is easier for supportability. It is the recommendedoption for this reason.There are a number of other limitations from an infrastructure point of view that need to beconsidered when allocating the number of drives per library. As a general point it is recommendedthat the number of tape drives per library does not exceed 64 due to the restrictions below:

• For iSCSI VTL devices a single Windows or Linux host can only access a maximum of 64devices. A single library with 63 drives is the most that a single host can access. Configuringa single library with more than 63 drives will result in not all devices in the library being seen

Overview 65

(which may include the library device). The same limitation could be hit with multiple librariesand fewer drives per library.

• A similar limitation exists for Fibre Channel. Although there is a theoretical limit of 255 devicesper FC port on a host or switch, the actual limit appears to be 128 for many switches andHBAs. You should either balance drives across FC ports or configure less than 128 drives perlibrary.

• Some backup applications will deliver less than optimum performance if managing manyconcurrent backup tape drives/streams. Balancing the load across multiple backup applicationmedia servers can help here.

Cartridge sizingThe size of a virtual cartridge has no impact on its performance and cartridges do not pre-allocatestorage. It is recommended that cartridges are created to match the amount of data being backedup. For example, if a full backup is 500 GB, the next larger configurable cartridge size is 800GB, so this should be selected.Note that if backups are to be offloaded to physical media elsewhere in the network, it isrecommended that the cartridge sizing matches that of the physical media to be used.

Number of libraries per applianceThe StoreOnce appliance supports the creation of multiple virtual library devices. If large amountsof data are being backed up from multiple hosts or for multiple disk LUNs on a single host, it isgood practice to separate these across several libraries (and consequently into multiple backupjobs). Each library has a separate deduplication “store” associated with it. Reducing the amountof data in, and complexity of, each store will improve its performance.Creating a number of smaller deduplication “stores” rather than one large store which receivesdata from multiple backup hosts could have an impact on the overall effectiveness of deduplication.However, generally, the cross-server deduplication effect is quite low unless a lot of common datais being stored. If a lot of common data is present on two servers, it is recommended that theseare backed up to the same virtual library.

• For best backup performance, configure multiple virtual libraries and use them all concurrently.

• For best deduplication performance, use a single virtual library and fully utilize all the drivesin that one library.

Backup application and configurationIn general backup application configurations for physical tape devices can be readily ported overto target a deduplicating virtual library with no changes; this is one of the key benefits of virtuallibraries – seamless integration. However considering deduplication in the design of a backupapplication configuration can improve performance, deduplication ratio or ease of data recoveryso some time spent optimizing backup application configuration is valuable.

Blocksize and transfer sizeAs with physical tape, larger tape block sizes and host transfer sizes are of benefit. This is becausethey reduce the amount of overhead of headers added by the backup application and also by thetransport interface. The recommended minimum is 256 KB block size, and up to 1 MB is suggestedif the backup application and operating system will support this.For HP Data Protector and EMC Networker Software a block size of 512 KB has been found toprovide the best deduplication ratio and performance balance and is the recommended block sizefor this application.Some minor setting changes to upstream infrastructure might be required to allow backups withgreater than 256 KB block size to be performed. For example, Microsoft’s iSCSI initiator

66 Virtual Tape Devices

implementation, by default, does not allow block sizes that are greater than 256 KB. To use ablock size greater than this you need to modify the following registry setting:nlnl

HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Class\nl

{4D36E97B-E325-11CE-BFC1-08002BE10318}\0000\Parameters

Change the REG_DWORD MaxTransferLength to “80000” hex (524,288 bytes), and restartthe media server – this will restart the iSCSI initiator with the new value.

Rotation schemes and retention policy

Retention policyThe most important consideration is the type of backup rotation scheme and associated retentionpolicy to employ. With data deduplication there is little penalty for using a large number of virtualcartridges in a rotation scheme and therefore a long retention policy for cartridges because mostdata will be the same between backups and will therefore be deduplicated.A long retention policy provides a more granular set of recovery points with a greater likelihoodthat a file that needs to be recovered will be available for longer and in many more versions.

Rotation schemeThere are two aspects to a rotation scheme which need to be considered:

• Full versus Incremental/Differential backups

• Overwrite versus Append of mediaFull versus Incremental/Differential backupsThe requirement for full or incremental backups is based on two factors, how often offsite copiesof virtual cartridges are required and speed of data recovery. If regular physical media copies arerequired, the best approach is that these are full backups on a single cartridge. Speed of datarecovery is less of a concern with a virtual library appliance than it is with physical media. Forexample, if a server fails and needs to be fully recovered from backup, this recovery will requirethe last full backup plus every incremental backup since (or the last differential backup). Withphysical tape it can be a time consuming process to find and load multiple physical cartridges,however, with virtual tape there is no need to find all of the pieces of media and, because thedata is stored on disk, the time to restore single files is lower due to the ability to randomly seekwithin a backup more quickly and to load a second cartridge instantly.Overwrite versus append of mediaOverwriting and appending to cartridges is also a concept where virtual tape has a benefit. Withphysical media it is often sensible to append multiple backup jobs to a single cartridge in orderto reduce media costs; the downside of this is that cartridges cannot be overwritten until the retentionpolicy for the last backup on that cartridge has expired. The diagram below shows cartridgecontaining multiple appended backup sessions some of which are expired and other that are valid.Space will be used by the StoreOnce appliance to store the expired sessions as well as the validsessions. Moving to an overwrite strategy will avoid this.With virtual tape a large number of cartridges can be configured for “free” and their sizes can beconfigured so that they are appropriate to the amount of data stored in a specific backup. Appendedbackups are of no benefit because media costs are not relevant in the case of VTL.

Rotation schemes and retention policy 67

Figure 39 Cartridges with appended backups (not recommended)

Our recommendations are:

• Target full backup jobs to specific cartridges, sized appropriately

• Reduce the number of appends by specifying separate cartridges for each incremental backupTaking the above factors into consideration, an example of a good rotation scheme where thecustomer requires weekly full backups sent offsite and a recovery point objective of every day inthe last week, every week in the last month, every month in the last year and every year in the last5 years might be as follows:

• 4 daily backup cartridges, Monday to Thursday, incremental backup, overwritten every week.

• 4 weekly backup cartridges, Fridays, full backup, overwritten every fifth week

• 12 monthly backup cartridges, last Friday of month, overwritten every 13th month.

• 5 yearly backup cartridges, last day of year, overwritten every 5 years.This means that in the steady state, daily backups will be small, and whilst they will always overwritethe last week, the amount of data overwritten will be small. Weekly full backups will alwaysoverwrite, but housekeeping has plenty of time to run over the following day or weekend orwhenever scheduled to run, the same is true for monthly and yearly backups.Total virtual tapes required in above rotation = 25Each backup job effectively has its own virtual tape.

Summary of VTL best practicesNOTE: The HP StoreOnce B6200 Backup system supports only FC VTLs.

• Make use of multiple network or Fibre Channel ports throughout your storage network toeliminate bottlenecks.

• For FC configurations, split virtual tape libraries and drives across multiple FC ports ( FC VTLis available on StoreOnce B6200, 4210 FC/ 4220/4420/4430 models).

• Configure multiple VTLs and separate data types across them; for example SQL to VTL1,Filesystem to VTL2, and so on.

• Configure larger “block sizes” within the backup application to improve performance.

• Disable any multiplexing configuration within the backup application.

• Disable any compression or encryption of data before it is sent to the StoreOnce appliance.

• Best throughput is achieved with multiple streams, the actual number per device/appliancevaries by model.

• Schedule physical tape offload/copy operations outside of other backup, replication orhousekeeping activities.

68 Virtual Tape Devices

• Tape drive emulation types have no effect on performance or functionality

• Configuring multiple tape drives per library enables multi-streaming operations per library forgood aggregate throughput performance.

• Do not exceed the recommended maximum concurrent backup streams per library andappliance if maximum performance is required.

• Target the backup jobs to run simultaneously across multiple drives within the library andacross multiple libraries. Keep the concurrent stream count high for best throughput.

• Create multiple libraries on the larger StoreOnce appliances to achieve best aggregateperformance

• Configure dedicated Individual libraries for backing up larger servers.

• Configure other libraries for consolidated backups of smaller servers.

• Separate libraries by data type if the best trade-off between deduplication ratio andperformance is needed

• Cartridge capacities should be set either to allow a full backup to fit on one cartridge or tomatch the physical tape size for offload (whichever is the smaller)

• Use a block size of 256KB or greater. For HP Data Protector and EMC Networker softwarea block size of 512 KB has been found to provide the best deduplication ratio and performancebalance.

• Disable the backup application verify pass for best performance.

• Remember that virtual cartridges cost nothing and use up very little space overhead. Don’t beafraid of creating “too many” cartridges. Define slot counts to match required retention policy.The D2DBS, ESL and EML virtual library emulations can have a large number of configurableslots and drives to give most flexibility in matching customer requirements.

• Design backup policies to overwrite media so that space is not lost to a large expired mediapool and media does not have different retention periods on the same piece of media.

• Reduce the number of appends per tape by specifying separate cartridges for each incrementalbackup, this improves replication performance and capacity utilization.

Summary of VTL best practices 69

10 NAS shares

NOTE: It is important to understand that the HP StoreOnce network share is intended to be usedONLY by backup applications that “back up to disk”. Do not use the NAS target device as adrag-and-drop general file store. The one exception to this rule is if you are using the NAS shareto seed an appliance for replication.

Operating system supportTwo interfaces are supported:• a CIFS interface for Windows networks

• a NFS interface for Linux and UNIX networksSee the HP StoreOnce Backup System user guide for more information about using the WebManagement Interface to create and configure NAS shares as targets for backup applications.Refer to the UNIX and Linux Configuration Guide for more information about the NFS interface.

Backup application supportNAS shares may be used with most applications that support backup to disk, including embeddedapplications, such as Oracle RMAN and VMWare VCB Agent. For the most up-to-date informationabout supported applications, refer to http://www.hp.com/go/ebs.

Shares and deduplication storesEach NAS share created on the StoreOnce system has its own deduplication “store”; any databacked up to a share will be deduplicated against all of the other data in that store, there is nooption to create non-deduplicating NAS shares and there is no deduplication between differentshares on the same StoreOnce appliance.Once a StoreOnce CIFS share is created, subdirectories can be created via Explorer. This enablesmultiple host servers to back up to a single NAS share but each server can back up to a specificsub-directory on that share. Alternatively a separate share for each host can be created.The backup usage model for StoreOnce has driven several optimisations in the NAS implementationwhich require accommodation when creating a backup regime:

• Only backup files larger than 24 MB will be deduplicated, this works well with backupapplications because they generally create large backup files and store them in configurablelarger containers . Please note that simply copying (by drag and drop for example) a collectionof files to the share will not result in the smaller files being deduplicated.

• There is a limit of 25000 files per NAS share, applying this limit ensures good replicationresponsiveness to data change. This is not an issue with many backup applications becausethey create large files and it is very unlikely that there will be a need to store more than 25000on a single share.

• A limit in the number of concurrently open files both above and below the deduplication filesize threshold (24 MB) is applied. This prevents overloading of the deduplication system andthus loss of performance.

When protecting a large amount of data from several servers with a StoreOnce NAS solution it issensible to split the data across several shares in order to realise best performance from the entiresystem by improving the responsiveness of each store. Smaller stores have less work to do in orderto match new data to existing chunks so they can perform faster.The best way to do this whilst still maintaining a good deduplication ratio is to group similar datafrom several servers in the same store. For example: keep file data from several servers in oneshare, and Oracle database backups in another share.

70 NAS shares


Maximum concurrently open filesThe table in Key parameters (page 115) shows the maximum number of concurrently open files pershare and per StoreOnce appliance for files above and below the 24 MB dedupe threshold size.A backup job may consist of several small metadata/control files (that are constantly being updated)and at least one large data file. In some cases, backup applications will hold open more than onelarge file. It is important not to exceed the maximum concurrent backup operations.If these thresholds are breached the backup application will receive an error from the StoreOnceappliance indicating that a file could not be opened and the backup will fail.The number of concurrently open files in the table do not guarantee that the StoreOnce appliancewill perform optimally with this number of concurrent backups, nor do they take into account thefact that host systems may report a file as having been closed before the actual close takes place,this means that the limits provided in the table could be exceeded without realizing it.Should the open file limit be exceeded an entry is made in the StoreOnce Event Log so the userknows this has happened. Corrective action for this situation is to reduce the overall concurrentbackups that are happening and have caused too many files to be opened at once, maybe byre-scheduling some of the backup jobs to take place at a different time.

Maximum number of NAS sharesThe total number of “devices” provided by a StoreOnce appliance is split between VTL, NAS andCatalyst devices..These devices may be all VTL, all NAS or any combination of NAS and VTLdevices. The following table illustrates some possible configurations.

Table 7 Maximum number of virtual devices per service set

Total number of devicesCatalystNASVTL

48 (maximum)0048

48 (maximum)0480

48 (maximum)4800

48 (maximum)02424

48 (maximum)0471

47 (less than maximum)0047

50 (more than maximum,you will not be able tocreate devices 49 and 50)

02030


48 (maximum)161616


Maximum number of files per NAS share and applianceThe HP StoreOnce NAS implementation is optimized for use with backup applications. Theseapplications create large backup files on the NAS share, which make much more efficient use ofdeduplication than simply copying files of various sizes to a deduplicating share. To improveperformance for small metadata files created by backup applications and to allow random accessto the header information at the beginning of backup files, the first 24 MB of any backed up filewill not be deduplicated. This non-deduplicated region is called the deduplication threshold.The HP StoreOnce Backup System imposes a limit on the number of files that can be stored oneach NAS share. The limit is 25000 files, which provides the ability to protect a large amount ofdata using a backup application. The limit is imposed in order to allow efficient use of datareplication.

Shares and deduplication stores 71

There are also limits on the number of open files greater than the deduplication threshold that areallowed per share and per appliance. These are the files that hold the backed-up data.Backup applications generally create a small number of additional files during a backup job inorder to store configuration details and catalog entries. Some of these small files will generally beupdated throughout the backup process and, in most instances, these files will be below thededuplication threshold. So, there is also a maximum number of open files that are the same sizeor smaller than the deduplication threshold that are allowed per appliance. See Keyparameters (page 115).

Maximum number of users per CIFS shareThe maximum number of users that may be configured when using “user” or AD authentication foraccess to a CIFS share is 50. This maximum is the total number of users per CIFS server and alsothe maximum that can be allocated access to any single CIFS shareDifferent users may access single NAS shares simultaneously, however, a file within a share mayonly be opened by one user at a time.

Maximum number of hosts per NFS shareThe maximum number of host systems that may be configured to access an NFS share is 50.This maximum is the total number of hosts per NFS server and also the maximum that can beallocated access to any single NAS share. A file within a share may only be opened by one userat a time.

CIFS share authenticationThe StoreOnce device provides three possible authentication options for the CIFS server:

• None – All shares created are accessible to any user from any client (least secure).

• User – Local (StoreOnce) User account authentication.

• AD – Active Directory User account authentication.None – This authentication mode requires no username or password authentication and is thesimplest configuration. Backup applications will always be able to use shares configured in thismode with no changes to either server or backup application configuration. However this modeprovides no data security as anyone can access the shares and add or delete data.User – In this mode it is possible to create “local StoreOnce users” from the StoreOnce managementinterface. This mode requires the configuration of a respective local user on the backup applicationmedia server as well as configuration changes to the backup application services. Individual userscan then be assigned access to individual shares on the StoreOnce appliance. This authenticationmode is ONLY recommended when the backup application media server is not a member of anAD Domain.AD – In this mode the StoreOnce CIFS server becomes a member of an Active Directory Domain.In order to join an AD domain the user needs to provide credentials of a user who has permissionto add computers and users to the AD domain. After joining an AD Domain access to each shareis controlled by Domain Management tools and domain users or groups can be given access toindividual shares on the StoreOnce appliance. This is the recommended authentication mode ifthe backup application media server is a member of an AD domain. It is the preferred option.Refer to the “HP StoreOnce Backup system user guide” for more information about configuringauthentication.

Backup application configurationThe HP StoreOnce Backup system NAS functionality is designed to be used with backup applicationsthat create large “backup files” containing all of the server backup data rather than applicationsthat simply copy the file system contents to a share.

72 NAS shares

When using a backup application with StoreOnce NAS shares the user will need to configure anew type of device in their backup application. Each application varies as to what it calls a backupdevice that is located on a StoreOnce device, for example it may be called a File Library, Backupto Disk Folder, or even Virtual Tape Library.Most backup applications allow the operator to set various parameters related to the NAS backupdevice that is created, these parameters are important in ensuring good performance in differentbackup configurations. Generic best practices can be applied to all applications as follows.

Backup file sizeBackup applications using disk/NAS targets will create one or more large backup files per backupstream; these contain all of the backed up data. Generally a limit will be set on the size that thisfile can get to before a new one is created (usually defaulting to 4–5 GB). A backup file is analogousto a virtual cartridge for VTL devices, but default file sizes will be much smaller than a virtualcartridge size (e.g. a virtual cartridge may be 800 GB).In addition to the data files, there will also be a small number of metadata files such as catalogueand lock files, these will generally be smaller than the 24 MB dedupe threshold size and will notbe deduplicated. These files are frequently updated throughout the backup process, so allowingthem to be accessed randomly without deduplication ensures that they can be accessed quickly.The first 24 MB of any backup file will not be deduplicated, with metadata files this means thatthe whole file will not be deduplicated, with the backup file the first 24 MB only will not bededuplicated. This architecture is completely invisible to the backup application which is merelypresented with its files in the same way as any ordinary NAS share would do so.It is possible that the backup application will modify data within the deduplicated data region; thisis referred to as a write-in-place operation. This is expected to occur rarely with standard backupapplications because these generally perform stream backups and either create a new file orappend to the end of an existing file rather than accessing a file in the middle.If a write-in-place operation does occur, the StoreOnce appliance will create a new backup itemthat is not deduplicated, a pointer to this new item is then created so that when the file is read thenew write-in-place item will be accessed instead of the original data within the backup file.If a backup application were to perform a large amount of write-in-place operations, there wouldbe an impact on backup performance – because of the random access nature that write in placecreates.Some backup applications provide the ability to perform “Synthetic Full” backups, these mayproduce a lot of write-in-place operations or open a large number of files all at once, it is thereforerecommended that Synthetic Full backup techniques are not used.Generally configuring larger backup container file sizes will improve backup performance anddeduplication ratio because:1. The overhead of the 24 MB dedupe region is reduced.2. The backup application can stream data for longer without having to close and create new

files.3. There is a lower percentage overhead of control data within the file that the backup application

uses to manage its data files.4. There is no penalty to using larger backup files as disk space is not usually pre-allocated by

the backup application.If possible the best practice is to configure a container file size that is larger than the completebackup will be (allowing for some data growth over time), so that only one file is used for eachbackup. Some applications will limit the maximum size to something smaller than that however,in which case, using the largest configurable size is the best approach.

Backup application configuration 73

Disk space pre-allocationSome backup applications allow the user to choose whether to “pre-allocate” the disk space foreach file at creation time, i.e. as soon as a backup file is created an empty file is created of themaximum size that the backup file can reach. This is done to ensure that there is enough disk spaceavailable to write the entire backup file. This setting has no value for StoreOnce devices becauseit will not result in any physical disk space actually being allocated due to the deduplication system.It is advised that this setting is NOT used because it can result in unrealistically high deduplicationratios being presented when pre-allocated files are not completely filled with backup data or, inextreme cases, it will cause a backup failure due to a timeout if the application tries to write asmall amount of data at the end of a large empty file. This results in the entire file having to bepadded-out with zeros at creation time, which is a very time consuming operation.

Block/transfer sizeSome backup applications provide a setting for block or transfer size for backup data in the sameway as for tape type devices. Larger block sizes are beneficial in the same way for NAS devicesas they are for virtual tape devices because they allow for more efficient use of the network interfaceby reducing the amount of metadata required for each data transfer. In general, set block or transfersize to the largest value allowed by the backup application.

Concurrent operationsFor best StoreOnce performance it is important to either perform multiple concurrent backup jobsor use multiple streams for each backup (whilst staying within the limit of concurrently open filesper NAS share). Backup applications provide an option to set the maximum number of concurrentbackup streams per file device; this parameter is generally referred to as the number of writers.Setting this to the maximum values shown in the table below ensures that multiple backups orstreams can run concurrently whilst remaining within the concurrent file limits for each StoreOnceshare.The table in Key parameters (page 115) shows the recommended maximum number of backupstreams or jobs per share to ensure that backups will not fail due to exceeding the maximum numberof concurrently open files. Note however that optimal performance may be achieved at a lowernumber of concurrent backup streams.These values are based on standard “file” backup using most major backup applications. If backingup using application agents (e.g. Exchange, SQL, Oracle) it is recommended that only one backupper share is run concurrently because these application agents frequently open more concurrentfiles than standard file type backups.

BufferingIf the backup application provides a setting to enable buffering for Read and/or Write this willgenerally improve performance by ensuring that the application does not wait for write or readoperations to report completion before sending the next write or read command. However, thissetting could result in the backup application inadvertently causing the StoreOnce appliance tohave more concurrently open files than the specified limits (because files may not have had timeto close before a new open request is sent). If backup failures occur, disabling buffered writes andreads may fix the problem, in which case, reducing the number of concurrent backup streams thenre-enabling buffering will provide best performance.

Overwrite versus appendThis setting allows the backup application to either always start a new backup file for each backupjob (overwrite) or continue to fill any backup file that has not reached its size limit before startingnew ones (append).

74 NAS shares

Appended backups should not be used because there is no benefit to using the append model,this does not save on disk space used.

Compression and encryptionMost backup applications provide the option to compress the backup data in software beforesending, this should not be implemented.Software compression will have the following negative impacts:1. Consumption of system resources on the backup server and associated performance impact.2. Introduction of randomness into the data stream between backups which will reduce the

effectiveness of StoreOnce deduplicationSome backup applications now also provide software encryption, this technology prevents eitherthe restoration of data to another system or interception of the data during transfer. Unfortunatelyit also has a very detrimental effect on deduplication as data backed up will look different in everybackup preventing the ability to match similar data blocks.The best practice is to disable software encryption and compression for all backups to the HPStoreOnce Backup system.

VerifyBy default most backup applications will perform a verify pass on each back job, in which theyread the backup data from the StoreOnce appliance and check against the original data.Due to the nature of deduplication the process of reading data is slower than writing as data needsto be re-hydrated. Thus running a verify will more than double the overall backup time. If possibleverify should be disabled for all backup jobs to StoreOnce, but trial restores should still happenon a regular basis.

Synthetic full backupsSome backup applications have introduced the concept of a “Synthetic Full” backup where afteran initial full backup, only file or block based incremental backups are undertaken. The backupapplication will then construct a full system recovery of a specific point in time from the originalfull backup and all of the changes up to the specified recovery point. In most cases this model willnot work well with a NAS target on a StoreOnce Backup system for one of two reasons.

• The backup application may post-process each incremental backup to apply the changes tothe original full backup. This will perform a lot of random read and write and write-in-placewhich will be very inefficient for the deduplication system resulting in poor performance anddedupe ratio.

• If the backup application does not post-process the data, then it will need to perform areconstruction operation on the data when restored, this will need to open and read a largenumber of incremental backup files that contain only a small amount of the final recoveryimage, so the access will be very random in nature and therefore a slow operation.

An exception to this restriction is the HP Data Protector Synthetic full backup which works well.However the HP Data Protector Virtual Synthetic full backup which uses a distributed file systemand creates thousands of open files does not. Check with your backup application or HP Salesperson for more details.

Summary of NAS best practices• Configure multiple shares and separate data types into their own shares.

• Adhere to the suggested maximum number of concurrent operations per share/appliance.• Choose disk container backup file sizes in backup software to meet the maximum size of the

backup data. For example, if a full backup is 500GB set the container size to be at least500GB . If this is not possible, make the backup container size as large as possible.

Summary of NAS best practices 75

• Each NAS share has a 25,000 file limit, some backup applications create large numbers ofsmall control files during backup to disk. If this is the case , it may be necessary to createadditional shares and distribute the backup across multiple shares.

• Disable software compression, deduplication and synthetic full backups.

• Do not pre-allocate disk space for backup files within the backup application.

• Best throughput is achieved with multiple streams, the actual number per device/appliancevaries by model.

• For NFS shares ensure the correct mount options are used to ensure in-order delivery andprovide better deduplication ratios. See the HP StoreOnce Linux and UNIX ConfigurationGuide for specific details.

• Configure bonded network ports for best performance.

• Monitor the number of files created in the share at regular intervals as there is a 25,000 filelimit per share

• For CIFS shares the recommended implementation is using AD authentication (see later)

• For NFS shares there is a specific mount option which ensures all data to the NFS share issent “in order” – which enables the best deduplication ratio. The name of the mount optionvaries according to the operating system; some operating systems also require an updatepackage to be installed to enable this. See the HP StoreOnce Linux and UNIX ConfigurationGuide for more details.

76 NAS shares

11 ReplicationWhen considering replication you are likely to be synchronizing data between different modelsof HP StoreOnce Backup Systems. The examples in this section are not specific to a particularmodel of HP StoreOnce Backup System.Replication can take place between multi-node and single-node StoreOnce Backup Systems. TheGUI for both refers to both Replication Targets and Sources as appliances. It is important tounderstand the different meaning of appliance within the multi-node and single-node environment.

• In a single-node StoreOnce Backup System, the appliance is the physical device or server thatcontains the data to be replicated. All mapping is done using the physical IP addresses of thetarget and source StoreOnce Backup Systems.

• In a multi-node StoreOnce Backup System, the appliance is the service set that contains thedata to be replicated. This means that each B6000 Backup System has at least two servicesets that can be selected as appliances. All mapping is done using the virtual IP addresses ofthe target and source service sets.

Within this chapter the term appliance and service set are synonymous.

What is replication?Replication is a standard term used to describe a way of synchronizing data between hardwarein two physical locations. It is the process of creating an exact match on the target appliance ofthe specified data from the source appliance. It is important to understand that no history is held;the target appliance always mirrors as soon as possible the current state of the data on the sourceappliance, which means that it is ready for use if the source share, library or appliance isunavailable. But it does not hold archive versions and is not an alternative to conventional backupwith multiple restore points. A Configuration Wizard is provided to take you through HP StoreOnceReplication configuration steps.StoreOnce replication is a concept that is used with VTL and NAS devices. The equivalent conceptfor Catalyst store is called Catalyst Copy.All three device types use a deduplication-enabled, low bandwidth transfer policy to replicate datafrom a device on a “replication source” StoreOnce Backup system to an equivalent device onanother “replication target” StoreOnce Backup system. The fundamental difference is that thebackup application controls Catalyst store copy operations, whereas all VTL and NAS replicationis configured and managed on the StoreOnce Management GUI.Replication provides a point-in-time “mirror” of the data on the source StoreOnce device at a targetStoreOnce Backup system on another site; this enables quick recovery from a disaster that hasresulted in the loss of both the original and backup versions of the data on the source site.Replication does not however provide any ability to roll-back to previously backed-up versions ofdata that have been lost from the source StoreOnce Backup system. For example, if a file isaccidentally deleted from a server and therefore not included in the next backup, and all previousversions of backup on the source StoreOnce Backup system have also been deleted, those fileswill also be deleted from a replication target device as the target is a mirror of exactly what is onthe source device. The only exception to this is if a Catalyst device type is used because the retentionperiods of data on the Target can be different (greater in most cases) than the retention periodsat the source – giving an additional margin on data protection.

NOTE: For examples on using Catalyst Copy with specific backup applications see HP StoreOnceBackup system Summary of Best Practices for VTL, NAS, StoreOnce Catalyst and Replicationimplementations with sizing and application configuration examples.

What is replication? 77

StoreOnce VTL and NAS replication overviewThe StoreOnce Backup system utilizes a propriety protocol for replication traffic over the Ethernetports; this protocol is optimized for deduplication-enabled replication traffic. An item (VTL Cartridgeor NAS file) will be marked ready for replication as soon as it is closed (or the VTL cartridgereturned to its slot). Replication works in a “round robin” process through the libraries and shareson a StoreOnce Backup system; when it gets to an item that is ready for replication it will start areplication job for that item assuming there is not already the maximum number of replication jobsunderway. Replication will first exchange metadata information between source and target toidentify the blocks of deduplicated data that are different; it will then synchronize the changesbetween the two appliances by transferring the changed blocks or marking blocks for removal atthe target appliance. Replication does trigger housekeeping on the Target Appliance.Replication will not prevent backup or restore operations from taking place. If an item is re-openedfor further backups or restore, then replication of that item will be paused to be resumed later orcancelled if the item is changed.Replication can also be configured to occur at specific times (via configurable blackout windows)in order to optimize bandwidth usage and not affect other applications that might be sharing thesame WAN link.VTL and NAS replication is configured between devices using “Mappings” and is not known tothe backup software but is controlled entirely by the StoreOnce appliance. Catalyst Copy iscontrolled entirely by the backup software and has no Mappings within the device to configure.A data import process is necessary to recover data from a target NAS or VTL device, But withCatalyst no backup application import is required because the additional copies are already knownto the backup software and do not need to be imported.

Replication usage models (VTL and NAS)There are four main usage models for replication using StoreOnce VTL and NAS devices shownbelow.

• Active/Passive – A StoreOnce system at an alternate site is dedicated solely as a target forreplication from a StoreOnce system at a primary location.

• Active/Active – Both StoreOnce systems are backing up local data as well as receivingreplicated data from each other.

• Many-to-One – A target StoreOnce system at a data center is receiving replicated data frommany other StoreOnce systems at other locations.

• N-Way – A collection of StoreOnce systems on several sites are acting as replication targetsfor other sites.

The usage model employed will have some bearing on the best practices that can be employedto provide best performance. The following diagrams show the usage models using VTL devicetypes.

78 Replication

Figure 40 Active to passive replication

Figure 41 Active to active replication

Replication usage models (VTL and NAS) 79

Figure 42 Many to Once replication

80 Replication

Figure 43 N-way replication

In most cases StoreOnce VTL and StoreOnce NAS replication is the same, the only significantconfiguration difference being that VTL replication allows multiple source libraries to replicate intoa single target library, NAS mappings however are 1:1, one replication target share may onlyreceive data from a single replication source share. In both cases replication sources libraries orshares may only replicate into a single target. However, with VTL replication a subset of thecartridges within a library may be configured for replication (a share may only be replicated inits entirety).

What to replicateStoreOnce VTL replication allows for a subset of the cartridges within a library to be mapped forreplication rather than the entire library (NAS replication does not allow this).Some retention policies may not require that all backups are replicated, for example dailyincremental backups may not need to go offsite but weekly and monthly full backups do, in whichcase it is possible to configure replication to only replicate those cartridges that are used for thefull backups.Reducing the number of cartridges that make up the replication mapping may also be useful whenreplicating several source libraries from different StoreOnce devices into a single target library ata data center, for example. Limited slots in the target library can be better utilized to take onlyreplication of full backup cartridges rather than incremental backup cartridges as well.Configuring this reduced mapping does require that the backup administrator has control overwhich cartridges in the source library are used for which type of backup. Generally this is done

What to replicate 81

by creating media pools with the backup application then manually assigning source librarycartridges into the relevant pools. For example the backup administrator may configure 3 pools:

• Daily Incremental, 5 cartridge slots (overwritten each week)

• Weekly Full, 4 cartridge slots (overwritten every 4 weeks)

• Monthly Full, 12 cartridge slots (overwritten yearly)Replicating only the slots that will contain full backup cartridges saves five slots on the replicationtarget device which could be better utilized to accept replication from another source library.

NOTE: The Catalyst equivalent of this requires the actual Backup policies to define which backupsto Catalyst stores are to be copied and which are not – so for example, you could configure onlyFull backups to be copied to Catalyst stores.

Appliance library and share replication fan in/fan outEach StoreOnce model has a different level of support for the number of other StoreOnce appliancesthat can be involved in replication mappings with it and also the number of libraries that mayreplicate into a single library on the device. The configuration settings are defined below.

The maximum number of target appliances that a source appliance can be paired withMax Appliance Fan Out

The maximum number of source appliances that a target appliance can be paired withMax Appliance Fan In

The maximum number of target libraries that may be replicated into from a single sourcelibrary on this type of appliance

Max Library Fan Out

The maximum number of source libraries that may replicate into a single target libraryon this type of appliance

Max Library Fan In

The maximum number of target NAS Shares that may be replicated into from a singlesource NAS Share on this type of appliance

Max Share Fan Out

The maximum number of source NAS Shares that may replicate into a single target NASShare on this type of appliance

Max Share Fan In

It is important to note that when utilizing a VTL replication Fan-in model (where multiple sourcelibraries are replicated to a single target library), the deduplication ratio may be better than isachieved by each individual source library due to the deduplication across all of the data in thesingle target library. However, over a large period of time the performance of this solution will beslower than configuring individual target libraries because the deduplication stores will be largerand therefore require more processing for each new replication job.

Concurrent replication jobsEach StoreOnce model has a different maximum number of concurrently running replication jobswhen it is acting as a source or target for replication. When many items are available for replication,this is the maximum number of jobs that will be running at any one time. As soon as one item hasfinished replicating another will start.For example, an HP 2620 may be replicating up to 4 jobs to a StoreOnce 4430, which may alsobe accepting another 44 source items from other StoreOnce systems. But the target concurrencyfor a 4430 is 96 so the target is not the bottleneck to replication performance. If total sourcereplication jobs are greater than 96 then the StoreOnce 4430 will limit replication throughput andreplication jobs will queue until a slot becomes available.

Apparent replication throughputIn characterizing replication performance we use a concept of “apparent throughput”. Sincereplication passes only unique data between sites there is a relationship between the speed atwhich the unique data is sent and how that relates to the whole backup apparently replicated

82 Replication

between sites. In all reporting on the StoreOnce Management GUI, the throughput in MB/sec isapparent throughput – think of this at the rate at which we are apparently replicating the backupdata between sites.

What actually happens in replication?Assuming the seeding process is complete (seeding is when the initial data is transferred to thetarget device), the basic replication process works like this:1. Source has a cartridge (VTL) or File (NAS) to replicate2. Source sends to target a “Manifest” that is a list of all the Hash codes it wants to send to the

target (the hash codes are what make up the cartridge/file/item)3. The target replies: “I have 98% of those hash codes already – just send the 2% I don’t have.”4. The source sends the 2% of hash codes the target requested.5. The VTL or NAS replication job executes and completes.The bigger the change rate of data, the more “mismatch” there will be and the higher the volumeof unique data that must be replicated over the WAN.

Limiting replication concurrencyIn some cases it may be useful to limit the number of replication jobs that can run concurrently oneither the source or target appliance. These conditions might be:1. There is a requirement to reduce the activity on either the source or target appliance in order

to allow other operations (e.g. backup/restore) to have more available disk I/O.2. The WAN Bandwidth is too low to support the number of concurrent jobs that may be running

concurrently. It is recommended that a minimum WAN bandwidth of 2Mb/sec is availableper replication job. If a target device can support for example 6 concurrent jobs, then 12Mb/s of bandwidth is required for that target appliance alone. If there are multiple targetappliances, the overall requirement is even higher. So, limiting the maximum number ofconcurrent jobs at the target appliance will prevent the WAN bandwidth being oversubscribedwith the possible result of replication failures or impact on other WAN traffic.

The Maximum jobs configuration is available from the StoreOnce Management GUI on the LocalSettings tab of the Replication – Configuration page. Other tabs on this page can be used to controlthe bandwidth throttling used for replication and the blackout windows that prevents replicationfrom happening at certain times.

WAN link sizingOne of the most important aspects in ensuring that a replication will work in a specific environmentis the available bandwidth between replication source and target StoreOnce systems. In most casesa WAN link will be used to transfer the data between sites unless the replication environment isall on the same campus LAN.It is recommended that the HP Sizing Tool (http://h30144.www3.hp.com/SWDSizerWeb/default.htm) is used to identify the product and WAN link requirements because the requiredbandwidth is complex and depends on the following:

• Amount of data in each backup

• Data change per backup (deduplication ratio)

• Number of StoreOnce systems replicating

• Number of concurrent replication jobs from each source

• Number of concurrent replication jobs to each target

• Link latency (governs link efficiency)

What actually happens in replication? 83

http://h30144.www3.hp.com/SWDSizerWeb/default.htm

http://h30144.www3.hp.com/SWDSizerWeb/default.htm

As a general rule of thumb, however, a minimum bandwidth of 2 Mb/s per replication job shouldbe allowed. For example, if a replication target is capable of accepting 8 concurrent replicationjobs (HP 4220) and there are enough concurrently running source jobs to reach that maximum,the WAN link needs to be able to provide 16 Mb/s to ensure that replication will run correctly atmaximum efficiency – below this threshold replication jobs may begin to pause and restart due tolink contention. It is important to note that this minimum value does not ensure that replication willmeet the performance requirements of the replication solution, a lot more bandwidth may berequired to deliver optimal performance.

Seeding and why it is requiredOne of the benefits of deduplication is the ability to identify unique data, which then enables usto replicate between a source and a target StoreOnce Backup system, only transferring the uniquedata identified. This process only requires low bandwidth WAN links, which is a great advantageto the customer because it delivers automated disaster recovery in a very cost-effective manner.The StoreOnce Management GUI reports bandwidth saving as a key metric of the replicationprocess and in general it is around the 95-98% mark (depending on data change rate).However prior to being able to replicate only unique data between source and target StoreOnceBackup system, we must first ensure that each site has the same hash codes or “bulk data” loadedon it – this can be thought of as the reference data against which future backups are comparedto see if the hash codes exist already on the target. The process of getting the same bulk data orreference data loaded on the StoreOnce source and StoreOnce target is known as “seeding”.

NOTE: With Catalyst the very first low bandwidth backup effectively performs its very ownseeding operation.

Seeding is generally a one-time operation which must take place before steady-state, low bandwidthreplication can commence. Seeding can take place in a number of ways:

• Over the WAN link – although this can take some time for large volumes of data. A temporaryincrease in WAN bandwidth provision by your telco can often alleviate this problem.

• Using co-location where two devices are physically in the same location and can use a GbEreplication link for seeding– (this is best for Active/Active, Active Passive configurations). Afterseeding is complete, one unit is physically shipped to its permanent destination.

• Using a “Floating” StoreOnce device which moves between multiple remote sites ( best formany to one replication scenarios)

• Using a form of removable media (physical tape or portable USB disks) to “ship data” betweensites.

The recommended way to accelerate seeding is by co-location of the source and target systemson the same LAN whilst performing the first replicate. This process will obviously involve movingone or both of the appliances and will thus prevent them from running their normal backup routines.In order to minimize disruption seeding should ideally only be done once; in this case all backupjobs that are going to be replicated must have completed their first full backup to the sourceappliance before commencing a seeding operation.Once seeding is complete there will typically be a 90+% hit rate, meaning most of the hash codesare already loaded on the source and target and only the unique data will be transferred duringreplication.It is good practice to plan for seeding time in your StoreOnce Backup system deployment plan asit can sometimes be very time consuming or manually intensive work. The Sizing Tool calculatesexpected seeding times over Wan and LAN to help set expectations for how long seeding willtake place. In practice a gradual migration of backup jobs to the StoreOnce appliance ensuresthere is not a sudden surge in seeding requirements but a gradual one, with weekends being usedto performer high volume seeding jobs.

84 Replication

During the seeding process it is recommended that no other operations are taking place on thesource StoreOnce Backup system, such as further backups or tape copies. It is also important toensure that the StoreOnce Backup system has no failed disks and that RAID parity initialization iscomplete because these will impact performance.When seeding over fast networks (co-located StoreOnce devices) it should be expected thatperformance to replicate a cartridge or file is similar to the performance of the original backup.

Replication models and seedingThe diagrams in Replication usage models (VTL and NAS) (page 78) indicate the different replicationmodels supported by HP StoreOnce Backup systems; the complexity of the replication models hasa direct influence on which seeding process is best. For example an Active – Passive replicationmodel can easily use co-location to quickly seed the target device, where as co-location may notbe the best seeding method to use with a 50:1, many to 1 replication model.

NOTE: HP StoreOnce Catalyst copy seeding follows the same processes outlined below with theadded condition that for multi-hop and one to many replication scenarios the seeding process mayhave to occur multiple times.

Table 8 Summary of seeding methods and likely usage models

CommentsConcernsBest forTechnique

Seeding time over WAN iscalculated automatically

This type of seeding shouldbe scheduled to occur over

Active -- Passive and Manyto 1 replication models with:nl

Seed over the WAN link

when using the Sizing toolfor StoreOnce.nl

weekends where at allpossible.

Initial Small Volumes ofBackup datanl

It is perfectly acceptable forcustomers to ask their link

ORnl

Gradual migration of largerbackup volumes/jobs toStoreOnce over time

providers for a higher linkspeed just for the periodwhere seeding is to takeplace.

Seeding time over LAN iscalculated automatically

This process involves thetransportation of completeStoreOnce units.nl

Active -- Passive, Active --Active and Many to 1replication models withsignificant volumes of data

Co-location (seed over LAN)

when using the Sizing toolfor StoreOnceThis method may not be

practical for large fan-in(> 1TB) to seed quickly andwhere it would simply take implementations e.g. 50:1too long to seed using aWAN link ( > 5 days)nl

because of the time delaysinvolved in transportation.

This process can only reallybe used as a “one off” whenreplication is firstimplemented.

This is really co-locationusing a spare StoreOnce.nl

Careful control over thedevice creation andco-location replication at the

Many to 1 replicationmodels with high fan inratios where the target must

Floating StoreOnce

The last remote siteStoreOnce can be used asthe floating unit.

target site is required. Seeexample below.

be seeded with severalremote sites at once.nl

Using the floating StoreOnceapproach means the deviceis ready to be used againand again for futureexpansion where moreremote sites might be addedto the configuration.

Seeding and why it is required 85

Table 8 Summary of seeding methods and likely usage models (continued)

CommentsConcernsBest forTechnique

Reduced shipping costs ofphysical tape media overactual StoreOnce units.nl

Relies on the backupapplication supporting thecopy process, e.g. Mediacopy or “object” copy” or“duplicate” or “cloning”

Suitable for all replicationmodels, especially whereremote sites are large (inter-continental) distances apart.nl

Well suited to target sitesthat plan to have a physical

Backup application Tapeoffload/ copy from sourceand copy onto target

Requires physical tapeconnectivity at all sites, ANDmedia server capability at

Tape archive as part of thefinal solution.nl

each site even if only for theseeding process.nl

Best suited for StoreOnceVTL deployments.nl

Backup application licensingcosts for each remote sitemay be applicableUnlikely to be used when

seeding HP StoreOnceB6200 Backup systems.

USB disks are typicallyeasier to integrate into

Multiple drives can be used– single drive maximum

USB portable disks, such asHP RDX series, can be

Use of portable disk drives -backup application copy ordrag and drop systems than physical tape

or SAS/FC disks.nl

capacity is about 3TBcurrently.

configured as Disk FileLibraries within the backupapplication software andused for “copies”nl

RDX ruggedized disks areOK for easy shipment

ORnl

between sites and costeffective.Backup data can be drag

and dropped onto theportable disk drive,transported and then dragand dropped onto theStoreOnce Target.nl

Best used for StoreOnceNAS deployments.nl

Do not use when seeding HPStoreOnce B6200 Backupsystems.

NOTE: Seeding methods are described in more detail in the next chapter.

Controlling ReplicationIn order to either optimize the performance of replication or minimize the impact of replication onother StoreOnce operations it is important to consider the complete workload being placed on theStoreOnce Backup system. By default replication will start quickly after a backup completes; thiswindow of time immediately after a backup may become very crowded if nothing is done toseparate tasks. In this time the following are likely to be taking place:

• Other backups to the StoreOnce Backup system which have not yet finished

• Housekeeping of the current and other completed overwrite backups

• Possible copies to physical tape media of the completed backupsThese operations will all impact each other’s performance, some best practices to avoid theseoverlaps are:

• Set replication blackout windows to cover the backup window period , so that replication willnot occur whilst backups are taking place.

• Set housekeeping blackout windows to cover the replication period, some tuning may berequired in order to set the housekeeping window correctly and allow enough time forhousekeeping to run.

• Delay physical tape copies to run at a later time when housekeeping and replication hascompleted. Preferably at the weekend

86 Replication

Replication blackout windowsThe replication process can be delayed from running using blackout windows that may be configuredusing the StoreOnce GUI. Up to two separate windows per day, which are at different times foreach day of the week, may be configured.The best practice is to set a blackout window throughout the backup window so that replicationdoes not interfere with backup operations. If tape copy operations are also scheduled, a blackoutwindow for replication should also cover this time.Care must be taken, however, to ensure that enough time is left for replication to complete. If it isnot, some items will never be synchronized between source and target and the StoreOnce Backupsystem will start to issue warnings about these items.The replication blackout window settings can be found on the StoreOnce Management Interfaceon the HP StoreOnce - Replication - Local Settings – Blackout Windows page.

Figure 44 Configuring replication blackout windows

Replication bandwidth limitingIn addition to replication blackout windows, the user can also define replication bandwidth limiting;this ensures that StoreOnce replication does not swamp the WAN with traffic, if it runs during thenormal working day.This enables blackout windows to be set to cover the backup window over the night time periodbut also allow replication to run during the day without impacting normal business operation.Bandwidth limiting is configured by defining the speed of the WAN link between the replicationsource and target, then specifying a maximum percentage of that link that may be used.Again, however, care must be taken to ensure that enough bandwidth is made available toreplication to ensure that at least the minimum (2 Mb/s per job) speed is available and more,depending on the amount of data to be transferred, in the required time.Replication bandwidth limiting is applied to all outbound (source) replication jobs from an appliance;the bandwidth limit set is the maximum bandwidth that the StoreOnce Backup system can use forreplication across all replication jobs.The replication bandwidth limiting settings can be found on the StoreOnce Management Interfaceon the HP StoreOnce - Replication - Local Settings - Bandwidth Limiting page.There are two ways in which replication bandwidth limits can be applied:

• General Bandwidth limit – this applies when no other limit windows are in place.

• Bandwidth limiting windows – these can apply different bandwidth limits for times of the dayA bandwidth limit calculator is supplied to assist with defining suitable limits.

Controlling Replication 87

Figure 45 Replication bandwidth settings

Source appliance permissionsIt is a good practice to use the Source Appliance Permissions functionality provided on theReplication - Partner Appliances tab to prevent malicious or accidental configuration of replicationmappings from unknown or unauthorized source appliances.See the HP StoreOnce Backup system user guide for information on how to configure SourceAppliance Permissions.Note the following changes to replication functionality when Source Appliance Permissions areenabled:

• Source appliances will only have visibility of, and be able to create mappings with, librariesand shares that they have already been given permission to access.

• Source appliances will not be able to create new libraries and shares as part of the replicationwizard process, instead these shares and libraries must be created ahead of time on the targetappliance.

Figure 46 Configuring source appliance permissions

88 Replication

12 Seeding methods in more detailWhile the concepts described in this chapter apply to all HP StoreOnce Backup systems, thediagrams in this chapter illustrate single node systems only. There is a separate chapter that illustrateshow to implement replication and seeding with the HP StoreOnce B6200 Backup system.

Seeding over a WAN linkWith this seeding method the final replication set-up (mappings) can be established immediately.In the active-passive replication model, WAN seeding over the first backup is, in fact, the firstwholesale replication.

Figure 47 Seeding over a WAN link, active-passive replication model

Seeding over a WAN link 89

In the active-active replication model, WAN seeding after the first backup at each location is, infact, the first wholesale replication in each direction.

Figure 48 Seeding over a WAN link, active-active replication model

90 Seeding methods in more detail

In the Many-to-One model, WAN seeding over the first backup is, in fact, the first wholesalereplication from the many remote sites to the Target site. Care must be taken not to run too manyreplications simultaneously or the Target site may become overloaded. Stagger the seeding processfrom each remote site.

Figure 49 Seeding over a WAN link, many-to-one replication model

Seeding over a WAN link 91

Co-location (seed over LAN)The following diagram illustrates co-location seeding from a remote site to Data Center, in anactive/passive replication model. The initial backup and replication takes place at the remote siteover the LAN. The StoreOnce appliance holding the replicated data is then transported to the DataCenter.

Figure 50 Co-location seeding in an Actve/Passive replication model

2. Replication over GbE link at remote site over LAN1. Initial backup

4. Re-establish replication with remote site over WAN3. Ship appliance to Data Center site

With this seeding method it is important to define the replication set-up (mappings) in advance sothat in say the Many to One example the correct mapping is established at each site the targetStoreOnce appliance visits before the target StoreOnce appliance is finally shipped to the DataCenter Site and the replication “re-established” for the final time.


The following diagram illustrates a many-to-one example.

Figure 51 Co-location seeding in an Actve/Passive replication model

2. Replication to Target StoreOnce appliance over GbElink at each remote site over LAN

1. Initial backup at each remote site

4. Finally take Target StoreOnce appliance to Data Centersite.

3. Move Target StoreOnce appliance between remote sitesand repeat replication.

5. Re-establish replication with remote sites over WAN

Co-location (seed over LAN) 93

Floating StoreOnce seedingIn this model co-location takes place at many remote sites using a floating StoreOnce target. TheStoreOnce target is transported between may sites and the taken to the Data Center. It is a usefulmodel for large-in fan scenarios.

Figure 52 Seeding using floating StoreOnce Backup system

2. Replication to floating StoreOnce Target appliance overGbE link at each remote site over LAN

1. Initial backup at each remote site

4. Finally take floating Target StoreOnce appliance to DataCenter site.

3. Move floating Target StoreOnce appliance betweenremote sites and repeat replication.

6. Establish final replication with remote sites.5. Establish replication from floating StoreOnce Target(now a Source) with Target StoreOnce at Data Center.Delete devices on floating Target StoreOnce appliance.nl

Repeat the process for further remote sites until all datahas been loaded onto the Data Center Target StoreOnceappliance. You may be able to accommodate 4 or 5 sitesof replicated data on a single floating StoreOnceappliance.

This “floating StoreOnce appliance” method is more complex because for large fan-in (many sourcesites replicating into single target site) the initial replication set up on the floating StoreOnceappliance changes as it is then transported to the data center, where the final replication mappingsare configured.The sequence of events is as follows:


1. Plan the final master replication mappings from sources to target that are required anddocument them. Use an appropriate naming convention e.g. SVTL1, SNASshare1, TVTL1,TNASshare1.

2. At each remote site perform a full system backup to the source StoreOnce appliance and thenconfigure a 1:1 mapping relationship with the floating StoreOnce appliance ” e.g. SVTL1 onRemote Site A -> FTVTL1 on floating StoreOnce. FTVTL1 = floating target VTL1.

3. Seeding remote site A to the floating StoreOnce appliance will take place over the GbE linkand should take only a few hours.

4. On the Source StoreOnce appliance at the remote site DELETE the replication mappings – thiseffectively isolates the data that is now on the floating StoreOnce appliance.

5. Repeat the process steps 1-4 at Remote sites B and C.6. When the floating StoreOnce appliance arrives at the central site, the floating StoreOnce

appliance effectively becomes the Source device to replicate INTO the StoreOnce applianceat the data center site.

7. On the Floating StoreOnce appliance we will have devices (previously named as FTVTL1,FTNASshare 1) that we can see from the Web Management Interface. Using the same masternaming convention as we did in step 1, set up replication which will necessitate the creationof the necessary devices (VTL or NAS) on the StoreOnce 4220 at the Data Center site e.g.TVTL1, TNASshare 1.

8. This time when replication starts up the contents of the floating StoreOnce appliance will bereplicated to the data center StoreOnce appliance over the GbE connection at the data centersite and will take several hours. In this example Remote Site A, B, C data will be replicatedand seeded into the StoreOnce 4220. When this replication step is complete, DELETE thereplication mappings on the floating StoreOnce appliance, to isolate the data on the floatingStoreOnce appliance and then DELETE the actual devices on the floating StoreOnce appliance,so the device is ready for the next batch of remote sites.

9. Repeat steps 1-8 for the next series of remote sites until all the remote site data has beenseeded into the StoreOnce 4220.

10. Now we have to set up the final replication mappings using our agreed naming conventiondecided in Step 1. This time we go to the Remote sites and configure replication again to theData Center site but being careful to use the agreed naming convention at the data centersite e.g. TVTL1, TNASshare1 etc.

This time when we set up replication the StoreOnce 4220 at the target site presents a list of possibletarget replication devices available to the remote site A. So in this example we would select TVTL1or TNASshare1 from the drop-down list presented to Remote Site A when we are configuring thefinal replication mappings. This time when the replication starts almost all the necessary data isalready seeded on the StoreOnce 4220 for Remote site A and the synchronization process happensvery quickly.

NOTE: If using this approach with Catalyst stores that do not rely on “mappings”, the FloatingStoreOnce appliance can be simply used to collect all the Catalyst Items at the Remote sites if aconsolidation model is to be deployed. If not, create a separate Catalyst store on the FloatingStoreOnce Appliance for each site.

Seeding using physical tape or portable disk driveIn this method of seeding we use a removable piece of media (like LTO physical tape or removableRDX disk drive acting as a disk Library or file library*) to move data from the remote sites to thecentral data center site. This method requires the use of the backup application software andadditional hardware to put the data onto the removable media.* Different backup software describes “disk targets for backup” in different ways e.g. HP DataProtector calls StoreOnce NAS shares “ DP File Libraries”, Commvault Simpana calls StoreOnceNAS shares “Disk libraries.”

Seeding using physical tape or portable disk drive 95

Figure 53 Seeding using physical tape and backup application

2. Copy to tape(s) or a disk using backup applicationsoftware on Media Server for NAS devices; only use simple

1. Initial backup to StoreOnce appliance

drag and drop to portable disk This technique is notpossible at Sites A & B unless a media server is present.

4. Copy tapes/disks into target appliance using backupapplication software on Media Server (or for portable disks

3. Ship tapes/disks to Data Center site.

only use drag and drop onto NAS share on the StoreOncetarget).

5. Establish replication.

Proceed as follows1. Perform full system backup to the StoreOnce Backup system at the remote site using the local

media server, e.g. at remote site C. The media server must also be able to see additionaldevices such as a physical LTO tape library or a removable disk device configured as a disktarget for backup.

2. Use the backup application software to perform a full media copy of the contents of theStoreOnce Backup system to a physical tape or removable disk target for backup also attachedto the media server. In the case of removable USB disk drives the capacity is probably limitedto 2 TB, in the case of physical LTO5 media it is limited to about 3 TB per tape, but of coursemultiple tapes are supported if a tape library is available. For USB disks, separate backuptargets for disk devices would need to be created on each removable RDX drive because wecannot span multiple RDX removable disk drives.

3. The media from the remote sites is then shipped (or even posted!) to the data center site.4. Place the removable media into a library or connect the USB disk drive to the media server

and let the media server at the data center site discover the removable media devices. Themedia server at the data center site typically has no information on what is on these piecesof removal media and we have to make the data visible to the media server at the data centersite. This generally takes the form of what is known as an “import” operation where the


removable media has to be registered into the catalog/database of the media server at thedata center site.

5. Create devices on the StoreOnce Backup system at the data center site using an agreedconvention e.g. TVTL1, TNASshare1. Discover these devices through the backup applicationso that the media server at the data center site has visibility of both the removable mediadevices AND the devices configured on the StoreOnce Backup system.

6. Once the removable media has been imported into the media server at the data center site itcan be copied onto the StoreOnce Backup system at the data center site (in the same way asbefore at step 2) and, in the process of copying the data , we seed the StoreOnce Backupsystem at the data center site. It is important to copy physical tape media into the VTL devicethat has been created on the StoreOnce Backup system and copy the disk target for backupdevice (RDX) onto the StoreOnce NAS share device that has been created on the StoreOnceBackup system at the data center site.

7. Now we have to set up the final replication mappings using our agreed naming convention.Go to the remote sites and configure replication again to the data center site, being carefulto use the agreed naming convention at the data center site e.g. TVTL1, TNASshare1 etc. Thistime when we set up replication the StoreOnce 4220 at the target site presents a list of possibletarget replication devices available to the remote site. So in this example we would selectTVTL1 or TNASshare1 from the drop-down list presented to remote site C when we areconfiguring the final replication mappings. This time when the replication starts almost all thenecessary data is already seeded on the StoreOnce 4220 for Remote site A so thesynchronization process happens very quickly.

The media servers are likely to be permanently present at the remote sites and data center site sothis is making good use of existing equipment. For physical tape drives/library connection at thevarious sites SAS or FC connection is required. For removable disk drives such as RDX a USBconnection is the most likely connection because it is available on all servers at no extra cost.If the StoreOnce deployment is going to use StoreOnce NAS shares at source and target sites theseeding process can be simplified even further by using the portable disk drives to drag and dropbackup data from the source system onto the portable disk. Then transport the portable disk to thetarget StoreOnce site and connect it to a server with access to the StoreOnce NAS share at thetarget site. Perform a drag and drop from portable disk onto the StoreOnce NAS share and thisthen performs the seeding for you!

NOTE: Drag and drop is NOT to be used for day to day use of StoreOnce NAS devices forbackup; but for seeding large volumes of sequential data this usage model is acceptable.

Only HP Data Protector, Symantec NetBackup and Symantec Backup Exec support HP StoreOnceCatalyst – but Catalyst stores can be “copied” to Tape or USB Disk using object copy (DP), duplicatecommands (NetBackup).

Seeding using physical tape or portable disk drive 97

13 Implementing replication with the HP B6200 Backupsystem

The main difference with the HP B6200 StoreOnce implementation is that replication is part of theservice set. Each service set (associated to Node 1, Node 2, et cetera) can handle a maximum of48 incoming concurrent replication jobs per node and can itself replicate OUT to up to 16 devices.If failover occurs, the replication load becomes incumbent on the remaining service set. Thereplication traffic will pause during the failover process and restart from the last checkpoint whenfailover has completed. This means that replication continues without the need for manualintervention but performance may deteriorate. Possible ways to improve this situation are:

• Dedicate a couplet as a replication target only (no backup targets). This will allow moreresources to be dedicated to replication in the event of failover.

• Stagger the replication load across different nodes in different couplets. Try not to overloada couplet that is responsible for replication.

Active/Passive and Active/Active configurationsFigure 54 shows an ideal situation where:

• Site B nodes are acting as replication targets only. Performance is guaranteed and all wehave to do is enable the replication windows and make allowances each day for housekeeping.

• The replication load at Site B is balanced across two nodes. In the event of failure of a nodeat Site B, replication performance will not be adversely affected, especially if the nodes atSite B are less than 50% loaded.

NOTE: If there are local backups at Site B as well to VTL7 and NAS3, the arrangement shownin Figure 56 would be the best practice.

Figure 52shows local backup devices VT7 and NAS7 at Site B on Couplet 1. We are still dedicatingnodes to act as replication targets, but they are now on Couplet 2 only. Because the load on thenodes in Couplet 2 is now increased, should a node fail in Couplet 2 on Site B there may benoticeable performance degradation on replication. This is because a single node has to handlea much larger load than in Figure 22. Careful sizing of the nodes in Couplet 2 on Site B to ensurethey are less than 50% loaded will ensure that even in failover mode replication performance canbe maintained.

98 Implementing replication with the HP B6200 Backup system

Figure 54 Using dedicated nodes for replication targets at the target site (Active/Passive replication)

Active/Passive and Active/Active configurations 99

Figure 55 Using dedicated nodes for replication targets at the target site for Active Passive, alongwith backup sources at Site B


In Figure 56 we deliberately provide one node on each couplet that is dedicated to replication.This simplifies the management, and the loading and performance is easier to predict. The waythe couplets are balanced also means that wherever a node fails over we do not lose all ourreplication performance. In the failover scenario the remaining node can still handle backup inone time window and replication in another time window so the overall impact of a failed nodeis not that damaging.

Figure 56 Using dedicated nodes for replication targets in an Active/Active configuration

Active/Passive and Active/Active configurations 101

Many to One configurationsThe other main usage model for the HP B6200 Backup system is in large-scale remote officedeployments where a fan-in of up to 384 replication jobs to a maximum-configuration HP B6200Backup System is possible (one stream per device). The sources (remote offices) are more likely tobe single-node HP StoreOnce StoreOnce Backup systems.For a large number of remote sites co-location is impractical, instead the Floating StoreOnce optionis recommended. Physical tape and seeding over aWAN link both have difficulties, due to capacityand bandwidth limitations.

Implementing floating StoreOnce seedingThis “floating StoreOnce” method is more complex because for large fan-in (many source sitesreplicating into a single target site) the initial replication setup on the floating StoreOnce changeswhen it is transported to the Data Center, where the final replication mappings are configured.The sequence of events is as follows:1. Plan the final master replication mappings from sources to target that are required and

document them. Use an appropriate naming convention, such as SVTL1 (Source VTL1),SNASshare1, TVTL1 (Target VTL1), TNASshare1.

2. At each remote site perform a full system backup to the source StoreOnce and then configurea 1:1 mapping relationship with the floating StoreOnce device, such as:nl

SVTL1 on Remote Site A -> FTVTL1 on floating StoreOnce where FTVTL1 = floating target VTL1.Seeding times at the remote site A will vary. If the StoreOnce at site A is an HP StoreOnce2620 Backup system, it is over a 1 GbE link and may take several hours. It will be faster if amodel with 10GbE replication links is used at the remote sites.

3. On the Source StoreOnce at the remote site DELETE the replication mappings – this effectivelyisolates the data that is now on the floating StoreOnce.

4. Repeat the process steps 1-3 at Remote sites B and C.5. When the floating StoreOnce arrives at the central site, the floating StoreOnce effectively

becomes the Source device to replicate INTO the HP B6200 Backup System at the Data Centersite.

6. On the floating StoreOnce we will have devices (previously named as FTVTL1, FTNASshare1) that we can see from the Management Console (GUI). Using the same master namingconvention as we did in step 1, set up replication which will necessitate the creation of thenecessary devices (VTL or NAS) on the B6200 at the Data Center site e.g. TVTL1, TNASshare1.

7. This time when replication starts up the contents of the floating StoreOnce will be replicatedto the Data Center B6200 over the 10 GbE connection at the Data Center site and will takeseveral hours. In this example Remote Site A, B, C data will be replicated and seeded intothe B6200. When this replication step is complete, DELETE the replication mappings on thefloating StoreOnce, to isolate the data on the floating StoreOnce and then DELETE the actualdevices on the floating StoreOnce, so the device is ready for the next batch of remote sites.

8. Repeat steps 1-7 for the next series of remote sites until all the remote site data has beenseeded into the HP B6200 Backup System.

9. Finally set up the final replication mappings using our agreed naming convention decided inStep 1. At the remote sites configure replication again to the Data Center site but be carefulto replicate to the correct target devices, by using the agreed naming convention at the datacenter site e.g. TVTL1, TNASshare1 etc.This time when we set up replication the B6200 at the target site presents a list of possibletarget replication devices available to the Remote Site A. So, in this example, we would selectTVTL1 or TNASshare1 from the list of available targets presented to Remote Site A when weare configuring the final replication mappings. This time when the replication starts almost all


the necessary data is already seeded on the B6200 for Remote Site A and the synchronizationprocess happens very quickly.

In some scenarios where a customer has larger remote storage locations the floating StoreOnceprocess can be used together with the smaller locations seeding over the WAN link.Another consideration is the physical logistics for some customers with 100+ locations, some beinginternational locations. The floating StoreOnce and co-location will be difficult, so the only optionis to schedule the use of increased bandwidth connections along with their infrastructure needs.The schedule is used to perform seeding at timed, phased slots.

Balancing Many-to-One replicationFor the many-to-one replication scenario, it is probably better to load balance the number ofincoming replication sources across the available nodes as shown in the diagram below.In Figure 25 we show the many-to-one replication scenario where we have grouped remote sites(VTL and NAS) together into bundles and have them replicating into multiple dedicated replicationtarget devices. The current recommendation with the HP B6200 Backup System is to keep the samerelationship between remote site VTLs and replication target VTLs, namely a 1:1 mapping.The deployment illustrated has the following benefits:

• Load balancing of remote sites: 40 sites are divided by 4 and then presented in bundles of10 to the replication targets. As more remote sites come on line they are also balanced acrossthe four replication target nodes.

• Site B backup devices can be managed and added to easily, and their loading on the nodeaccurately monitored. Similarly, the replication target nodes have a single function (replicationtargets) which makes their behavior more predictable.

• In a failover situation, the performance impact on either backup or replication is likely to belower because the backup load at Site B nodes and the replication load at Site B nodes arelikely to run in separate windows at separate times.

Many to One configurations 103

Figure 57 Balancing many-to-one replication sources across all available nodes

Replication and load balancingThe specification for a B6200 service set is that it can accept up to a maximum of 48 concurrentreplication streams from external sources. If more than 48 streams are replicating into a B6200node, some streams will be put on hold until a spare “replication slot” becomes available.Being a replication target is more demanding of resources than being a replication source, this iswhy we recommend allocating dedicated replication targets to specific nodes.The example detailed on the following page shows a full system approach and is a good overviewof what is required.Note that:

• Each service set on each node is relatively at the same load (load balancing is a manualprocess)

• Each node has a single function, VTL backup targets node, NAS backup targets node,Replication target. This makes management and load assessment easier


• FC SAN 1 with its larger number of hosts and capacities is spread over four nodes all withmaximum storage capacity. There are at least eight streams per node to provide goodthroughput performance

• All the NAS target backups have been grouped together on node 5 and 6 on 10GbE – thesecould be VMWare backups which generally require a backup to NAS target. Again all NAStargets are balanced equally across nodes 5 and 6 and, in the event of failover, performancewould be well balanced at around 50% of previous performance for the duration of thefailed-over period.

• FC SAN 2 has smaller capacity hosts connected via FC. Nodes 7 and 8 are the least loadedhosts, so this couplet is the obvious candidate for use as the replication target.

• Keep it simple and easy to understand – that’s the key.

Figure 58 Fully load-balanced analysis of a typical implementation

Many to One configurations 105

14 HousekeepingHousekeeping is the process whereby space is reclaimed and is best scheduled to occur in quietperiods when no backup or replication is taking place. If insufficient time is allocated tohousekeeping, there is a risk that housekeeping jobs will stack up – effectively “hogging” capacitySo, there are two factors to consider:

• Is housekeeping interfering with performance, in which case you may wish to set blackoutwindows, when housekeeping will not occur, see below.Housekeeping blackout windows are configurable (up to two periods in any 24 hours) so,even if the “clean up” scripts run in the backup software, the housekeeping will not triggeruntil the blackout window is closed.

• Are backup and replication jobs scheduled to allow housekeeping time to complete?Running backup, restore, tape offload and replication operations with no break (i.e. 24 hoursa day) will result in housekeeping never being able to complete. Configuring backup rotationschemes correctly is very important to ensure the maximum efficiency of the product; correctconfiguration of backup rotation schemes reduces the amount of housekeeping that is requiredand creates a predictable load. For example, large housekeeping loads are created if largenumbers of cartridges are manually erased or re-formatted. In general all media overwritesshould be controlled by the backup rotation scheme so that they are predictable.Housekeeping also applies when data is replicated from a source StoreOnce appliance to atarget StoreOnce appliance – the replicated data on the target StoreOnce appliance triggershousekeeping on the target StoreOnce appliance to take place. Blackout windows are alsoconfigurable on the target devices.

Housekeeping Blackout windowThis is a period of time (up to 2 separate periods in any 24 hours) that can be configured in theStoreOnce appliance during which the I/O intensive process of Housekeeping WILL NOT run. Themain use of a blackout window is to ensure that other activities such as backup and replicationcan run uninterrupted and therefore give more predictable performance. Blackout windows mustbe set on BOTH the source StoreOnce appliance and Target StoreOnce appliance. See HPStoreOnce Backup system Best Practices with Sizing Tool and StoreOnce Catalyst worked examplesfor a fully worked example of configuring a complex StoreOnce environment including settinghousekeeping windows.

NOTE: With the HP B6200 Backup system, housekeeping blackout windows are configured perservice set.

Without a housekeeping blackout window set, the housekeeping can interfere with the backupjobs because both are competing for disk I/O.By setting a housekeeping blackout window appropriately from 12:00 to 00:00 we can ensurethe backups and replication run at maximum speed because the housekeeping is scheduled to runwhen the device is idle.There is a worked example in HP StoreOnce Backup system Summary of Best Practices with SizingTool and StoreOnce Catalyst worked examples.

Tuning housekeeping using the StoreOnce GUISome tuning is required to determine how long to set the housekeeping windows; this is achievedusing the StoreOnce Management Interface and the reporting capabilities which we will nowexplain.

106 Housekeeping

On the StoreOnce Management Interface go to the Housekeeping page; a series of graphs anda configuration capability is displayed.There are four tabs on the Housekeeping page: Overall, Libraries, Shares and StoreOnce Catalyst.The Overall tab shows the total housekeeping load on the appliance. The other tabs can be usedto select the device type and monitor housekeeping load on individual named VTL, NAS sharesor Catalyst stores. Note how the Housekeeping blackout window configuration setting is shownbelow the Housekeeping status. The housekeeping blackout window is set on an appliance basisnot an individual device type basis.

NOTE: With the HP B6200 Backup system, housekeeping statistics are per service set.

Figure 59 Housekeeping jobs received versus housekeeping jobs processed

The Housekeeping load on the target replication devices is generally higher than on the sourcedevices and must be monitored/observed on those devices – you cannot monitor the targethousekeeping load from the source device.The key features within this section are:

• Housekeeping Statistics:nlnl

Status has three options: OK if housekeeping has been idle within the last 24 hours, Warningif housekeeping has been processing nonstop for the last 24 hours, Caution if housekeepinghas been processing nonstop for the last 7 days.nlnl

Last Idle is the date and time when the housekeeping processing was last idle.nlnl

Time Idle (Last 24 Hours) is a percentage of the idle time in the last 24 hours.nlnl

Time Idle (Last 7 Days) is a percentage of the idle time in the last 7 days.• Load graph (top graph): will display what levels of load the StoreOnce appliance is under

when housekeeping is being processed. However this graph is intended for use whenhousekeeping is affecting the performance of the StoreOnce appliance (e.g. housekeeping

Tuning housekeeping using the StoreOnce GUI 107

has been running nonstop for a couple of hours), therefore if housekeeping is idle most of thetime no information will be displayed.

Figure 60 Housekeeping load graph

1. Housekeeping under control2. Housekeeping out of control, not being reduced over time

In the above graph we show two examples, one where the housekeeping load increases and thensubsides, which is normal, and another where the housekeeping job continues to grow and growovertime. This second condition would be a strong indication that the housekeeping jobs are notbeing dealt with efficiently, maybe the housekeeping activity window is too short (housekeepingblackout window too large), or we may be overloading the StoreOnce appliance with backupand replication jobs and the unit may be undersized.Another indicator is the Time Idle status, which is a measure of the housekeeping empty queuetime. If % idle over 24 hours is = 0 this means that the box is fully occupied and that is not healthy,but this may be OK if the % idle over 7 days is not 0 as well. For example, if the appliance is 30%idle over 7 days then we are probably operating within reasonably safe limits.Signs of housekeeping becoming too high are that backups may start to slow down or backupperformance becomes unpredictable. Corrective actions if idle time is low or the load continuesto increase are:

• Use a larger StoreOnce appliance or add additional shelves to increase I/O performance.

• Restructure the backup regime to remove appends on tape or keep appends on separatecartridges – as the bigger the tapes (through appends,) the more housekeeping they generatewhen they are overwritten.

• Increase the time allowed for housekeeping to run by reducing the housekeeping blackoutwindows

If you do set up housekeeping blackout windows (up to two periods per day, 7 days per week),be careful as you cannot set a blackout time from say 18:00 to 00:00 but you must set 23:59. Inaddition there is a Pause Housekeeping button, but use this with caution because it pauseshousekeeping indefinitely until you restart it!Finally, remember that it is best practice to set housekeeping blackout windows on both the sourceand target devices. There is a worked example in HP StoreOnce Backup system Summary of BestPractices with Sizing Tool and StoreOnce Catalyst worked examples.

108 Housekeeping

15 Tape OffloadTerminology

Direct Tape OffloadThis is when a physical tape library device is connected directly to the rear of the StoreOnceBackup system. This offload feature is not currently supported on HP StoreOnce Backup system.

Backup application Tape Offload/Copy from StoreOnce Backup systemThis is the preferred way of moving data from a StoreOnce Backup system to physical tape. Thedata transfer is managed entirely by the backup software, multiple streams can be copiedsimultaneously and StoreOnce NAS, Catalyst store and VTL emulations can be copied to physicaltape. Both the StoreOnce Backup system and the physical tape library must be visible to the backupapplication media server doing the copy and some additional licensing costs may be incurred bythe presence of the physical tape library. Using this method, entire pieces of media (completevirtual tapes or NAS shares) may be copied OR the user can select to take only certain sessionsfrom the StoreOnce Backup system and copy and merge them onto physical tape. These techniquesare known as “media copy” or “object copy” respectively. All copies of the data are tracked bythe backup application software using this method and it is the tape offload method HP recommends.When reading data in this manner from the StoreOnce Backup system the data to be copied mustbe read from the StoreOnce appliance and “reconstructed” then copied to physical tape. Just aswith the backup process – the more parallel backup streams to the StoreOnce appliance the fasterthe backup will proceed, Similarly the larger the number of parallel reads generated for the tapecopy, the faster the copy to tape will take place – even if this means less than optimal usage ofphysical tape media.Scheduling tape offload to occur at less busy periods, such as weekends, is also highlyrecommended, so that the read process has maximum I/O available to it.

Backup application Mirrored Backup from Data SourceThis again uses the backup application software to write the same backup to two devicessimultaneously and create two copies of the same data. For example, if the monthly backups mustbe archived to tape, a special policy can be set up for these mirror copy backups. The advantageof this method is that the backup to physical tape will be faster and you do not need to allocatespecific time slots for copying from StoreOnce Backup system to physical tape. All copies of thedata are tracked by the backup application software.

Terminology 109

Tape Offload/Copy from StoreOnce Backup system versus Mirrored Backup fromData Source

A summary of the supported methods is shown below.

Table 9 Tape Offload/Copy

For optimum performancenl

For easiest integrationnl

Separate physical tape mirrored backupBackup application copy to tape

This is a parallel activity. The host backs up to theStoreOnce appliance and the host backs up to tape. It hasthe following benefits:

The backup application controls the copy from theStoreOnce appliance to the network-attached tape driveso that:

• The backup application still controls the copy location• It is easier to find the correct backup tape

• •The scheduling of copy to tape can be automated withinthe backup process

It has the highest performance because there are noread operations and reconstruction from the StoreOnceappliance

Constraints:Constraints:• • Streaming performance will be slower because data

must be reconstructed.• It requires the scheduling of specific mirrored backup

policies.• This method is generally only available at the “Source”

side of the backup process. Offloading to tape at thetarget site can only use the backup application copy totape method.

When is Tape Offload required?• Compliance reasons or company strategy dictate Weekly, Monthly, Yearly copies of data be

put on tape and archived or sent to a DR site. Or a customer wants the peace of mind thathe can physically “hold” his data on a removable piece of media.

• In a StoreOnce Replication model it makes perfect sense for the data at the StoreOnce DR siteor central site to be periodically copied to physical tape and the physical tape be stored atthe StoreOnce site (avoiding offsite costs) yet still providing long term data retention.

• The same applies in a StoreOnce Catalyst Copy model. However, the StoreOnce CatalystCopy feature allows the backup application to incorporate tape offload, as well as CatalystStore copy between StoreOnce appliances into a single backup job specification. The followingexamples relate to StoreOnce Replication.

Catalyst device typesThe visibility, flexibility and integration of Catalyst stores into the backup software is one of thekey advantages of HP StoreOnce Catalyst - especially because the replicated copies are alreadyknown to the backup application.

110 Tape Offload

Figure 61 StoreOnce Catalyst Copy offload to tape drive

2. Low bandwidth Catalyst Copy1. Catalyst Copy command

3. Rehydration and full bandwidth copy to tape

VTL and NAS device types

Figure 62 Backup application tape offload at StoreOnce target site for VTL and NAS device types

2. StoreOnce low bandwidth replication1. Backup data written to StoreOnce Source

3. All data stored safely at DR site. Data at StoreOnce target (written by StoreOnce source via replication) must beimported to Backup Server B before it can be copied to tape.

NOTE: Target Offload can vary from one backup application to another in terms of importfunctionality. Please check with your vendor.

When is Tape Offload required? 111

Figure 63 Backup application tape offload at StoreOnce source site for VTL and NAS device types

1. Copy StoreOnce device to physical tape; this uses the backup Copy job to copy data from the StoreOnce applianceto physical tape and is easy to automate and schedule, it has a slower copy performance.

2. Mirrored backup; specific backup policy used to back up to StoreOnce and Physical Tape simultaneously (mirroredwrite) at certain times (monthly). This is a faster copy to tape method.

As can be seen in the diagrams above – offload to tape at the source site is somewhat easierbecause the backup server has written the data to the StoreOnce Backup system at the source site.In the StoreOnce Target site scenario (Figure 30), some of the data on the StoreOnce Backupsystem may have been written by Backup Server B (local DR site backups, maybe) but the majorityof the data will be on the StoreOnce Target via low bandwidth replication from StoreOnce Source.In this case, the Backup Server B has to “learn” about the contents of the StoreOnce target beforeit can copy them and the typical way this is done is via “importing” the replicated data at theStoreOnce target into the catalog at Backup Server B, so that it knows what is on each replicatedvirtual tape or StoreOnce NAS share. Copy to physical tape can then take place. These limitationsdo not exist if HP StoreOnce Catalyst device types are used.

HP StoreOnce Optimum Configuration for Tape OffloadOptimizing tape offload from HP StoreOnce Backup System is achieved by reading multiple datastreams simultaneously into a backup application, which combines the data streams into a singledata stream (multiplexing). This single data stream is now fast enough to send to a HP LTO UltriumTape Device and maintain streaming, hence ensuring optimal throughput and minimal offloadtime.To achieve multiple data streams on a HP StoreOnce Backup System, create an offload job in thebackup application, which reads from multiple objects stored on the HP StoreOnce Backup Systemsimultaneously, then using the backup application’s multiplexing option to write to a single HP LTOphysical tape.

Offload Considerations

VTL Cloning/Media Copy to Physical TapeThis process involves transferring all backup data held on a VTL cartridge directly to a physicaltape making an identical copy of the data. This type of tape offload generally does not supportappending, therefore it is best practice to match the VTL cartridge size to the Physical cartridgesize. (May Not Apply To All Backup Applications)

112 Tape Offload

HP StoreEver Tape LibrariesHP Half-Height Tape Drives for LTO 5 and LTO 6 have equal Data Transfer Rates to the Full-Heightversions. This allows an HP StoreEver MSL 2024 to have two Half-Height LTO Drives with nodecrease in performance giving maximum “performance density”.

Backup ApplicationTo achieve optimum offload performance the backup application must be capable of multiplexingoffload data to a HP LTO Ultrium Tape, and the backup application server must be capable ofingesting multiple streams from the HP StoreOnce Backup System at the same speed as it can writeto HP LTO Ultrium Tape.

HP StoreOnce Optimum Tape Offload ConfigurationThe table below represents the optimum configuration of Tape Drives and Data Streams foroffloading from an HP StoreOnce Backup System.

HP LTO 4HP LTO 5HP LTO 6

DataStreams

PhysicalDrives

RecommendedPhysicalLibrary

DataStreams

PhysicalDrives


DataStreams

PhysicalDrives


HPStoreOnce

62MSL2024

82MSL2024

82MSL2024

HPStoreOnce2700 and2620iSCSI

123MSL4048

123MSL4048

123MSL4048

HPStoreOnce4210iSCSI &FC

93MSL4048

93MSL4048

93MSL4048

HPStoreOnce4210 & 1Shelf

124MSL4048

104MSL4048

123MSL4048

HPStoreOnce4500,4220

84MSL4048

104MSL4048

93MSL4048

HPStoreOnce4500,4220 & 1Shelf

116ESL G395ESL G3124MSL4048

HPStoreOnce4420


HPStoreOnce4420 & 1Shelf


HPStoreOnce4420 & 2Shelves

HP StoreOnce Optimum Tape Offload Configuration 113


HPStoreOnce4420 & 3Shelves

158ESL G3147ESL G3126ESL G3HPStoreOnce4700 and4430

158ESL G3147ESL G3126ESL G3HPStoreOnce4700 and4430 & 1Shelf

88ESL G3147ESL G3126ESL G3HPStoreOnce4700 and4430 & 2Shelves

88ESL G3147ESL G3126ESL G3HPStoreOnce4700 and4430 & 3Shelves

NOTE: Split the number of data streams evenly between the physical drives. For example, twodrives with six streams is configured as three data streams per physical drive. If you have an unevennumber of streams, for example five drives with nine streams, four drives are configured with twodata streams each and the fifth drive has a single stream.

114 Tape Offload

16 Key parametersStoreOnce B6200 Backup

Table 10 Key parameters for HP StoreOnce B6200 Backup

Four coupletsThree coupletsTwo coupletsOne coupletStoreOnce Backup products running software3.0.0 and later

Devices

Up to 512Up to 384Up to 256Up to 128Max Addressable Disk Capacity (TB) – assuming2TB drives

38428819296Max Number Devices (VTL + NAS shares )

15361152768384Total maximum concurrent streams (backup/restores/inbound replication)

Replication

8642Max VTL Library Rep Fan Out

16161616Max VTL Library Rep Fan In

64483216Max Rep Fan Out +

38428819296Max Rep Fan In

128966432Max Concurrent Rep Jobs as Source

38428819296Max Concurrent Rep Jobs Target

Physical Tape Copy Support

NoNoNoNoSupports direct attach of physical tape device

N/AN/AN/AN/AMax Concurrent Tape Attach Jobs Appliance

VTL

19201440960480Max VTL drives (384) and medium changers (96)- (combined)

15361152768384Max VTL Drives

3.23.23.23.2Max Cartridge Size (TB)

16384163841638416384Max Slots Per Library (D2DBS, EML-E, ESL-E LibType)

24,48,9624,48,9624,48,9624,48,96Max Slots Per Library (MSL2024,MSL4048,MSL8096 Lib Type)

19201440960480Max virtual devices( drives & medium changers)configurable per FC ports

1024768512256Recommended Max Concurrent backup streams( mix of VTL & NAS)

12121212Recommended Max Concurrent Backup Streamsper Library

StoreOnce B6200 Backup 115

Table 10 Key parameters for HP StoreOnce B6200 Backup (continued)

Four coupletsThree coupletsTwo coupletsOne coupletStoreOnce Backup products running software3.0.0 and later

NAS

25000250002500025000Max files per share

15361152768384Max number of streams if only CIFS target sharesconfigured (no VTL)

768586384192Max number of streams if only NFS target sharesconfigured (no VTL)

1024768512256Recommended Max Concurrent Backup Streams(mix of VTL & NAS)

12121212Recommended Max Concurrent Backup Streamsper Share

StoreOnce Catalyst

512384256128Catalyst Command Sessions per service set = 64

38428819296Maximum Concurrent outbound copy jobs perservice set = 48

15361152768384Maximum Concurrent inbound data and copyjobs per service set = 192

StoreOnce 2700, 4500 and 4700 BackupTable 11 Key parameters for HP StoreOnce 2700, 4500 and 4700 Backup

StoreOnce 4700StoreOnce 4500StoreOnce 2700StoreOnce Backup products running software 3.8.0 andlater

Devices

160365.5Usable Disk Capacity (TB) (With full expansion)

50248Max Number Devices (VTL/NAS/Catalyst)

Replication



842Max Appliance Rep Fan Out

50248Max Appliance Rep Fan In

482412Max Appliance Concurrent Rep Jobs Source

964824Max Appliance Concurrent Rep Jobs Target


NoNoNoSupports direct attach of physical tape device

N/AN/AN/AMax Concurrent Tape Attach Jobs Appliance

116 Key parameters

Table 11 Key parameters for HP StoreOnce 2700, 4500 and 4700 Backup (continued)

StoreOnce 4700StoreOnce 4500StoreOnce 2700StoreOnce Backup products running software 3.8.0 andlater

VTL

2009632Max VTL Drives Per Library/Appliance

3.23.23.2Max Cartridge Size (TB)

4096102496Max Slots Per Library (D2DBS, EML-E, ESL-E Lib Type)

24,48,9624,48,9624,48,96Max Slots Per Library (MSL2024,MSL4048,MSL8096 LibType)

1289648Max active streams per store

644816Recommended Max Concurrent Backup Streams perappliance

1264Recommended Max Concurrent Backup Streams per Library

NAS


1286448Max NAS Open Files Per Share > DDThreshold*

1286448Max NAS Open Files Per Appliance > DDThreshold*

640320240Max NAS Open Files Per Appliance concurrent

644824Recommended Max Concurrent Backup Streams perappliance

1264Recommended Max Concurrent Backup Streams per Share

StoreOnce Catalyst

643216Catalyst Command Sessions

482412Maximum Concurrent outbound copy jobs per appliance

1929648Maximum Concurrent inbound data and copy jobs perappliance

StoreOnce 2610/2620, 4210/4220 and 4420/4430 BackupTable 12 Key parameters for HP StoreOnce 2610/2620, 4210/4220 and 4420/4430 Backup

StoreOnce4430

StoreOnce4420

StoreOnce4220

StoreOnce4210

nl

StoreOnce2620

nl

StoreOnce2610

nl

StoreOnce Backup products runningsoftware 3.4.0 and later iSCSI/FCiSCSIiSCSI

Devices

76381892.51Usable Disk Capacity (TB) (With fullexpansion)

5050241684Max Number Devices(VTL/NAS/Catalyst)

Replication


StoreOnce 2610/2620, 4210/4220 and 4420/4430 Backup 117

Table 12 Key parameters for HP StoreOnce 2610/2620, 4210/4220 and 4420/4430 Backup(continued)

StoreOnce4430

StoreOnce4420

StoreOnce4220

StoreOnce4210

nl

iSCSI/FC

StoreOnce2620

nl

iSCSI

StoreOnce2610

nl

iSCSIStoreOnce Backup products runningsoftware 3.4.0 and later


884422Max Appliance Rep Fan Out

5050241684Max Appliance Rep Fan In

484824241212Max Appliance Concurrent Rep JobsSource

969648484824Max Appliance Concurrent Rep JobsTarget


NoNoNoNoNoNoSupports direct attach of physical tapedevice

N/AN/AN/AN/AN/AN/AMax Concurrent Tape Attach JobsAppliance

VTL

20020096643216Max VTL Drives Per Library/Appliance

3.23.23.23.23.23.2Max Cartridge Size (TB)

40964096102410249696Max Slots Per Library (D2DBS, EML-E,ESL-E Lib Type)

24,48,9624,48,9624,48,9624,48,9624,48,9624,48,96Max Slots PerLibrary (MSL2024,MSL4048,MSL8096Lib Type)

12812896644832Max active streams per store

646448482416Recommended Max ConcurrentBackup Streams per appliance

12126644Recommended Max ConcurrentBackup Streams per Library

NAS


12812864644832Max NAS Open Files Per Share >DDThreshold*

12812864644832Max NAS Open Files Per Appliance> DDThreshold*

64064012812811296Max NAS Open Files Per Applianceconcurrent

646448482416Recommended Max ConcurrentBackup Streams per appliance

12126644Recommended Max ConcurrentBackup Streams per Share

118 Key parameters

Table 12 Key parameters for HP StoreOnce 2610/2620, 4210/4220 and 4420/4430 Backup(continued)

StoreOnce4430

StoreOnce4420

StoreOnce4220

StoreOnce4210

nl

iSCSI/FC

StoreOnce2620

nl

iSCSI

StoreOnce2610

nl

iSCSIStoreOnce Backup products runningsoftware 3.4.0 and later

StoreOnce Catalyst

646432321616Catalyst Command Sessions

484824244812Maximum Concurrent outbound copyjobs per appliance

19219296964812Maximum Concurrent inbound dataand copy jobs per appliance

StoreOnce 2610/2620, 4210/4220 and 4420/4430 Backup 119

About this guideThis guide provides conceptual information about the following HP StoreOnce Backup systems:

• HP StoreOnce B6200 Backup system

• HP StoreOnce 2700 Backup system




• HP StoreOnce 4210/4220 Backup system

• HP StoreOnce 4420/4430 Backup system

Intended audienceThis guide is intended for users who install, operate and maintain the HP StoreOnce Backup System.

Related documentationIn addition to this guide, the following document provides related information:

• ‘Start here' poster for an overview of the installation information in this guide (available inEnglish, French, German and Japanese)

• HP StoreOnce Backup system CLI Reference Guide

• HP StoreOnce Backup system Linux and UNIX Reference Guide

• HP StoreOnce Backup system User Guide

• HP StoreOnce Backup system Maintenance and Service GuideYou can find these documents from the HP Support Center website:

http://www.hp.com/support/

Query on your product name and then select the Product Manuals link.

Document conventions and symbolsTable 13 Document conventions

ElementConvention

Cross-reference links and e-mail addressesBlue text: Table 13 (page 120)

website addressesBlue, underlined text: http://www.hp.com

Bold text • Keys that are pressed

• Text typed into a GUI element, such as a box

• GUI elements that are clicked or selected, such as menuand list items, buttons, tabs, and check boxes

Text emphasisItalic text

120

http://www.hp.com/support/

http://www.hp.com

Table 13 Document conventions (continued)

ElementConvention

Monospace text • File and directory names

• System output

• Code

• Commands, their arguments, and argument values

Monospace, italic text • Code variables

• Command variables

Emphasized monospace textMonospace, bold text

WARNING! Indicates that failure to follow directions could result in bodily harm or death.

CAUTION: Indicates that failure to follow directions could result in damage to equipment or data.

IMPORTANT: Provides clarifying information or specific instructions.

NOTE: Provides additional information.

HP technical supportFor worldwide technical support information, see the HP support website:

http://www.hp.com/support

Before contacting HP, collect the following information:

• Product model names and numbers

• Technical support registration number (if applicable)

• Product serial numbers

• Error messages

• Operating system type and revision level

• Detailed questions

HP websitesFor additional information, see the following HP websites:

• http://www.hp.com

• http://www.hp.com/go/ebs

• http://www.hp.com/go/connect

• http://www.hp.com/go/storage

• http://www.hp.com/service_locator

• http://www.hp.com/support/manuals

• http://www.hp.com/support/downloads

Documentation feedbackHP welcomes your feedback.

HP technical support 121

http://www.hp.com/support

http://www.hp.com


http://www.hp.com/go/connect

http://www.hp.com/go/storage

http://www.hp.com/service_locator


http://www.hp.com/support/downloads

To make comments and suggestions about product documentation, please send a message [email protected]. All submissions become the property of HP.

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