RealTime 7.1.1 for Microsoft SQL

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This document is provided for informational purposes only. All warranties relating to the information in thisdocument, either express or implied, are disclaimed to the maximum extent allowed by law. The information inthis document is subject to change without notice. Copyright 2012 Symantec Corporation. All rightsreserved. Symantec, the Symantec logo and NetBackup are trademarks or registered trademarks ofSymantec Corporation or its affiliates in the U.S. and other countries. Other names may be trademarks of their

respective owners

NetBackup RealTime 7.1.1 for

Microsoft SQL server in 2008 and

2008R2 cluster environmentIf you have any feedback or questions about this document pleaseemail them to [email protected] stating thedocument title.
mailto:[email protected]:[email protected]:[email protected]


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NetBackup RealTime 7.1.1 for Microsoft SQL server in 2008 and 2008R2 cluster environment

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Document Control

Contributors

Who Contribution

Ashutosh Badve Principle Author

Adonijah Park Reviewer/contributor

Shilpa Umarjee Reviewer/contributor

Samer Mahajan Reviewer/contributor

Revision History

Version Date Changes

1.0 15-Feb-2012

Related Documents

Version Date Title

Table of Contents

Product Overview 1

Protecting Microsoft SQL with RealTime 2

Integration with NetBackup 3

Restoring With RealTime 4

Pros and cons 5

Appendix A: Terminology 6


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NetBackupRealTime 7.1.1 for Microsoft SQL server in 2008 and 2008R2 cluster environment

Page 1

Product Overview

Continuous Data Protection (CDP) is a methodology that continuously captures data modifications (diskwrites) and stores changes independently of the primary disk (on secondary disk). CDP provides theability to access and recover data to the exact state as it existed at any previous point in time.

The NetBackup RealTime Protection product uses CDP technology to deliver data protection with thebest RPO and RTO. It taps into the I/O operations of the host to the primary disk and captures everyblock as it is changes. Streams of changes (CDP Stream) are kept in the SAN based storage for apredefined duration of time.

Figure 1: NetBackup RealTime data flow

As an application sends I/O down to the disk, the NetBackup RealTime client sends a duplicate write tothe RealTime server as a CDP Stream. NetBackup RealTime can then reconstruct an image or snapshotof the primary storage as it existed at any point in the past. With NetBackup RealTime, it is not necessaryto store the snapshots on the primary storage.

As a part of the NetBackup Platform, RealTime enables a different method for moving data off primarystorage and off host for backups, but it retains the robust management, recovery, and applicationintegration that NetBackup customers have relied on for years. Backup scheduling and storage lifecyclepolicies are managed via the NetBackup GUI or CLI like the traditional NetBackup Snapshot Policy

NetBackup treats RealTime as a special type of Snapshot. The end result is a series of snapshots thatcan be used for recovery from NetBackup. The advantage is that the snapshots exist on secondarystorage so they take up no space on the primary storage. The snapshots being on a separate physicalsystem are protected from failure or corruption of the primary storage system.


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The actual point in time for a Snapshot as scheduled by NetBackup is marked by placing a marker in theCDP Stream at the same time as it catalogs an event. For example, if the CDP Stream withoutNetBackup Snapshot Client looks like:

An equivalent CDP Stream with the NetBackup Snapshot Client integration would look like:

Blocks marked as letters (A, B, C) represent the changed block of data kept in historical order. Blocksnamed Snap# and Bkp are markers inserted by NetBackup to identify snapshots or backup events.

Additionally, this configuration also enables:

Restoration to any point in time between the backups.

168 snapshots for a week long timeline (assuming hourly snapshot backups)

Reduced storage requirements

Management through the familiar NetBackup user interface

Instant access to the data after a crash

RealTime stores the changes in its CDP Stream; thus you can recover from a snapshot or a backup, andrecover to any time in between the marked events by requesting the data image.

With standard disk based snapshots (for example: BCVs) there is a limit to the number of copies you cankeep. You may keep 2-4 snapshots in addition to the daily media backup and then recycle them. Foursnapshots per day can leave the data vulnerable for up to 6 hours. With RealTime, you can create aninfinite number of snapshots without any additional cost because each snapshot consumes no additional.You can now schedule NetBackup to perform a snapshot every hour.

NetBackup RealTime integrates with other products of NetBackup. A NetBackup administrator uses

familiar tools and does not have to change the backup routine. The changes are identical to a new array.

There is a new snapshot type (RealTime) to choose from. Just as with a standard snapshot, an image ofthe data can be presented to the application for immediate access after a data loss. The benefit is that amore granular recovery point can be chosen from the timeline. In the case of data corruption, you want togo back to the moment before the corruption; RealTime uses the historical data which can be used forrestore by using copy back method. Currently since only copy back method is supported which isequivalent to current NetBackup traditional restore, restores can take some time according to the datasize. Since the product has the capability to do rollback restore, future releases will focus on improvingthe RTO by rolling back only the changed blocks.

Protecting Microsoft SQL with RealTime

A typical Microsoft cluster environment is shown in the below figure. For SAN connectivity and otherstorage requirement for RealTime please see the RealTime Administrator guide.

BkpSnap2

DCSnap1

BA FSnap

3E

FEDCBA


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StorageFor

RealTime

RealTimeServer

Figure 2: Microsoft cluster environment

For protecting whole Microsoft cluster using NetBackup RealTime the pre-requisites are as follows:

Install the NetBackup RealTime client on all the nodes in the cluster.

The cluster virtual name is DNS resolvable Expose Monitor LUN to all Microsoft cluster nodes and RealTime appliance.

a. This LUN can be as small as 1GB in size.b. You need at least two monitor LUNs from each array (If Production storage is provided from

multiple arrays).c. The normal storage array LUN is logically classified as Monitor LUN in RealTime.d. It is used by RealTime to understand whether one particular node in the cluster is down or

operating.e. It should be made online in disk management snap-in. Do not put any file system and mount

it. It is only for the use of RealTime.

Production Storage should be visible to RealTime appliance for SAN sync. RealTime only readsfrom these LUNs for doing SAN sync.

On meeting the above requirements you can add the Cluster object via the RealTime GUI or CLI. This

Cluster object contains all the nodes in the cluster.

On adding the cluster object in the RealTime GUI or CLI, you can define the RealTime applicationcontainer which has the assets to be protected in cluster. On applying the protection, RealTimesynchronizes the production LUNs to make a mirror copy of it. While you protect and track the changeshappening on the active cluster SQL instances, if the SQL cluster resources failover to other nodes in thecluster, it does not impact the RealTime protection. You can continue to track and protect every IOhappening on the cluster. Even when a node in the cluster reboots, you get a black out window whichsignifies that protection is not available for that duration.

RealTime would ideally support all the application clusters build on top of MSCS cluster technology whichare supported by NetBackup snapshot client. Although, currently RealTime is only qualified with MSCSSQL cluster.

Integration with NetBackup

NetBackup RealTime provides the ability to mark specific points within the CDP stream as a snapshot.NetBackup Snapshot Client uses this functionality to create a snapshot at the transaction consistent pointin time and prepare it for backup and/or instant recovery. When you back up a database while in thetransaction consistent state, the database recovers quickly. There are several steps in this backupprocess.

Backup is initiated using NetBackup SQL agent


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NetBackup SQL agent puts SQL database in quiescent state.

Snapshot is created.

In this configuration NetBackup RealTime acts as the snapshot provider. Instead ofcreating a physical copy of the data, RealTime inserts an annotation into the CDP Streamto mark the point in time as a snapshot. This operation is quick and requires no additionaldisk space. It can be performed as often as an application is put in a quiescent state.

Snapshot Client uses API to communicate with the snapshot provider. It does notdistinguish between the methods used underneath. This is why Snapshot Clientrecognizes RealTime snapshot as any other array or software based snapshot.

The event is cataloged with NetBackup

If a backup to the media is requested, Snapshot Client performs an additional step. It requests an accessto the snapshot from the provider, in this case RealTime. RealTime provide an image of the data as it wasat the time of the annotation. The image is mounted to the NetBackup client or Media Server and used asa source for the backup to the tape. NetBackup catalogues this event as a backup. While a backup isperformed from the RealTime snapshot, the application continues to run, and RealTime continues torecord new changes.

The data flow described above is also presented in Figure 3.

Figure 3: Data flow

The snapshots created during the backup process can be used for cloning the database for processing

on the same or on an alternate host.

Restoring With RealTime

There are two ways to restore the SQL database:

Normal NetBackup restores procedure for SQL database from a snapshot.

Restore through NetBackup allows granular restore capabilities with full database restore. Therestoration of the database from the snapshot is invoked.

DB Server

NBU

Media

NBU

DB RealTimeStorage

NBU Catalog

1am S1(snap only)

7am S2(snap only)

1pm S3(snap only)7pm 4(snap+bckp)

1am S5(snap only)

RealTime

ServerRealTime

PIT Image


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Page 5

Standalone RealTime GUI (Using RealTime GUI to recover to any point in time).

This is the only method not available through the standard NetBackup user interface. It allows forrestoration to the point in time immediately before the crash. Only the transactions which werecommitted are available on the snapshot copy. It resembles the state of the data as it would beafter a system crash. Before opening the database, Microsoft SQL has to go through the internalrecovery process. Transactions that have not been committed are rolled back.

These methods can be applied in the case of a disaster and data corruption.

When choosing the recovery method, you should consider the best scenario for the specific environment.It has to be carefully planned in advance when designing a backup solution. What is the best recoveryscenario? The same RPO can be accomplished using several methods. Which one presents the bestRTO for your application?

When using RealTime you have to decide between:

Using RealTime without inserting frequent snapshot markers: There is no application downtime.At the restore time Microsoft SQL has to roll back the database to the transaction consistentstate.

Using RealTime with frequent snapshot type backups: There are penalty of application quiescent,but SQL database has all the transactions without doing any recovery procedure.

The best practices for scheduling a backup with RealTime are:

Perform a snapshot and backup to a storage unit once a week.

Create a TimeImageTM

view snapshot every hour. When deciding on the frequency of thesnapshots, note down the time required for snapshot backup to complete.

Pros and cons

This configuration offers a good return on investment. RealTime snapshots provide an unlimited numberof snapshots without taking up any disk space. There is initial investment in the storage to be used byRealTime, but it can be a tier lower than the production storage. The size of initial storage isapproximately 1.5 times the size of the protected data.

RealTime should be considered a step in the Data Protection Life Cycle. It is best to use it for short term

protection. Restores from RealTime are done for a quick recovery to a recent point in time. Creating amedia based backup from a RealTime based snapshot is recommended to enable long term retention.Currently this can be done by using snapshot and copy to storage unit option in NetBackup schedule.Future releases will have ability to do delayed backup to storage unit from a specified snapshot by usingSLP (storage life cycle policy) feature in NetBackup.

RealTime snapshot can be used for off-host or remote processing (backups, reporting, etc) and fordatabase cloning.

Adding a new cluster node to already protected cluster is not supported currently with RealTime. In thiscase you have to reapply RealTime protection to Microsoft cluster.

Microsoft Windows 2003 MSCS clusters are not supported.

Only alternate client backups are supported in cluster environment. Alternate client could be one of the

cluster nodes but we need to specify actual hostname of that host while specifying alternate host inNetBackup policy.

RealTime has a presence on the application host in the form of a kernel driver. There is a smallperformance penalty associated with it. The overhead is less than 5%, equivalent to that of a softwarebased mirror. On Windows RealTime kernel driver is signed and certified by Microsoft.

Since RealTime is a flexible product, minimal scripting can enhance its usage to utilize its full potential.


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In the future RealTime will add replication support, extending its use to the disaster recovery space. Byreplicating across the Data Centers it will provide the ability for remote backups, continuous dataprotection between remote sites; and failover capabilities.

NetBackup RealTime utilizes NetBackup for SQL Database Agent, and NetBackup Snapshot Client. Thecharacteristics of these products are inherited in RealTime and were discussed separately except wherea variation was specifically noted.

Appendix A: Terminology

Annotation - A record of a user-initiated action. RealTime server records annotations, which can beviewed through the Annotations screen.

Application - An instance of an application. Applications are directly accessed by the user. Examplesinclude: SAP, Share point, NetBackup, a file server, or a database sandbox with SQL server instances.

Application Host - SAN based host on which an application runs, also known as the production host,application server, or production server.

Asset - Assets are only used by applications. They are not directly accessed by the user. An asset candepend on other assets. Examples include: data, configurations, file-systems, volumes, LUNs, physical

storage, servers, SQL instances inside Share point, or Oracle databases inside SAP.Consistency Group - A group of LUNs that are common to an application.

Production host The SAN host on which a targeted application runs, also known as the applicationhost, application server, or production server.

Production image - A store within the RealTime store that keeps a copy of the production image.

Production Store - Storage that the application uses for reading/writing.

Production Volume - The primary storage for the protected application

RealTime Protection (RTP) - A protection method of RealTime that maintains a history of all changes toapplication data and allows recovery to any point on the timeline. RealTime protects against local datacorruption and provides the TimeImage

TMview side view and Production Restore features. RealTime is

the next step in the evolution of data protection and recovery. RealTime provides snapshot, backup, andrestore functionality with much finer grain control compared to existing disk and tape based solutions.

RealTime Recovery Manager- A term for the GUI that drives the RealTime Server.

RealTime Server - A soft appliance operating in Fibre Channel SANs that provides data protectionrecovery services.

RealTime Store - The collection of storage used by the RealTime Server Cluster for collecting the timeordered writes. Internally, this may be broken up, such as into a Production Image store, an Indexingstore, a Log, a Journal store or Scratch space for holding writes to a TimeImage

TMview, or an Event

store.

Snapshot - A TimeImageTM

view of the production store.

Soft appliance - A term for packaging software that runs on a standard x86 box. No specialized

hardware or ASICs are required.

Splitter- The host splitter (VxSplitter) or Data Tap (VxDataTap).

TimeImageTM

view - An exact reproduction of a specified Consistency Group at a specific point in time.When the RealTime server generates a TimeImage

TMview, that image is made available via new virtual

host-side TimeImageTM

view volumes. A SAN host, used specifically as the TimeImageTM

view host, canaccess the TimeImage

TMview just as if it were the up-to-date RealTime server Consistency Group, and

can manipulate the TimeImageTM

view Consistency Group. However, the TimeImageTM

view view iscompletely independent of the up-to-date Consistency Group maintained in the MirrorStore volume.


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TimeStore volume - The area of the RealTime servers dedicated storage reserved to hold both thetimeline and all internal information associated with the data protection services.

vLUN (virtual logical unit number) - A LUN that is virtual for the RealTime server, and is exposed by theRealTime target mode driver. A vLUN is treated as a normal LUN by an application host.

MSCS - Microsoft cluster server


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RealTime 7.1.1 for Microsoft SQL

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