Reduxio Solution for Citrix® XenServer 7 · |4 TableofContents Introduction 6 SolutionArchitecture...

REDUXIO SOLUTIONFOR CITRIX® XENSERVER 7

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Revisions

Jan 1, 2017 Initial revision.

Feb 5, 2018 Revised look & feel, added SR creation and deletion through CLI, space reclamation.

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Table of Contents

Introduction 6

Solution Architecture 6

Supported Configurations 6

Hardware Configuration 7

Software Configuration 7

Overview 8

The Business Challenge 8

Reduxio Solution for XenServer 9

Overview 9

Use Cases 9

Configuration 10

Overview 10

iSCSI Settings 10

Multipathing 10

Networking 10

Storage Provisioning 11

Creating an SR using CLI 12

Create an LVM SR 12

Create an ext3 SR 13

Deleting an SR using CLI 14

Delete an LVM SR 14

Delete an ext3 SR 14

Reclaim Space 15

Expanding Capacity 15

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BackDating™ 18

Concepts 18

History Timeline 18

Bookmarks 19

Clones 20

Recovering Data 21

Recovering SRs 21

Clone and Revert 22

Recover an SR using Cloning 23

Recover a SR using Revert 27

Troubleshooting 31

Log File Locations 31

Common Problems 31

Multipathing Problems 31

VM creation fails with “The attempt to create a VDI failed” 32

VM startup fails with “The SR failed to complete the operation” 32

Conclusion 33

References 34

Reduxio Documentation 34

Citrix Documentation 34

Introduction | 6

Introduction

Reduxio Solution for Citrix XenServer 7 describes the Reduxio solutions available for Citrix XenServer

virtualization customers. It provides instructions for the installation, configuration, and management of the

Reduxio HX Series storage system in a XenServer environment.

Solution Architecture

The Reduxio HX Series storage system is configured with one or more high capacity SRs. VM files are globally

“NoDuped”—deduped and compressed—expanding the total usable capacity of the system. Operating

system and application binaries are stored once and kept in memory. This leaves enough space—almost

the entire system’s capacity—available for application and user data.

The solution can be managed using native tools:

• Reduxio system: Reduxio Storage Manager (RSM) or ReduxioCLI.

• XenServer host – XenCenter, SSH shell.

Supported Configurations

Reduxio supports various storage configurations for XenServer environments:

Hypervisor Servers running XenServer v6.x/7.x or higher

Management Software • Reduxio TimeOS v2.x., v3.x

• XenCenter 6.x/7.x.

Storage Storage Repositories (SRs) on Reduxio volumes: block size 512 bytes, up to 2

TB (larger volume sizes are not supported by Citrix)

SRs are globally “NoDuped” and compressed, expanding the total

usable capacity of the system.

Introduction | 7

Hardware Configuration

The following hardware components were used in this reference architecture:

Qty. Hardware component Description

1 Reduxio HX Series dual-controller, 256 GB RAM,

8x 800GB MLC SSDs, 16x 2 TB 7.2k RPM SATA

disks

Reduxio HX Series storage system

2 Dell R620, dual-socket Intel Xeon E5-2650 v2 @

2.60 GHz (total 32 virtual cores), 256 GB RAM

Citrix XenServer servers

1 Mellanox 10GbE switch Interconnect between ESXi hosts and Reduxio

HX Series

1 Lenovo ThinkPad X1 Carbon Administration host

1 Apple iPad (second generation) Mobile administration

Software Configuration

The following software components were used in this reference architecture:

Qty. Software Component Description

3 XenServer v6.x/7.x XenServer hypervisors: two for virtual servers,

one for infrastructure and management VMs

Overview | 8

Overview

Implementing a virtual infrastructure in an organization raises various business challenges. Selecting a

storage infrastructure that is cost-effective but at the same time provides high performance and high

availability is the key to a successful deployment.

The Business Challenge

The abundance of virtualized environments is an evidence to their many benefits. Customers are finding

that virtualization improves the availability, manageability, and agility of their IT systems. However, what

about performance, scalability and data protection? Virtualization, which once served only a portion of the

environment, is now the core platform for nearly all IT environments—anywhere from the virtual desktop to

the data center’s most mission critical applications. This market shift towards massive consolidation has

created new challenges to storage administrators:

• Performance Scalability: Consolidating many applications onto a single system creates a storage

bottleneck. The aggregated I/Os from all hypervisors are sent to the storage concurrently, in a highly

random workload. For example, a specific application server produces a 1,000 IOPS. Virtualizing 200

servers with this load requires a storage system that can handle 20,000 IOPS.

• Storage Efficiency: A major benefit of virtualization is that it simplifies the integration between servers

and applications. This creates a high demand for capacity required to store the set of operating systems

and applications. For example, a server with multiple applications installed would typically require 50 GB

or more. Virtualizing just 200 servers with that capacity would already require 10 TB stored on high

performance media. A typical enterprise nowadays implements hundreds to thousands of VMs,

amounting to tens of terabytes required just to host the VMs.

• VM Availability: A consolidated server environment is as available as its VM storage layer. Customers

expect 100% availability for their virtual infrastructure. This requires high availability, not only at the

service level, but also at the data level. Storage repositories must be accessible even after major

hardware and software component failures. This challenges existing storage architectures, which only

provide an infrequent protection to storage repositories.

Overview | 9

Reduxio Solution for XenServer

Overview

Reduxio Storage is the most intuitive solution for virtualization infrastructure based on XenServer. The

solution consists of the following components:

Reduxio Storage System: The Reduxio enterprise flash storage arrays, based on Reduxio’s TimeOS™

storage operating system, allows you to recover application data to any second in the past, eliminates most

of the complexity associated with managing storage, and provides exceptional performance and efficiency,

far exceeding anything available today.

The Reduxio system provides considerably higher performance and more effective capacity for VMs than

traditional SAN, and provides VM and storage repository recoverability to any second in the past without

upfront administration.

Use Cases

There are various use cases for Reduxio Storage in XenServer environments:

Server Virtualization A highly efficient, high performance storage platform for XenServer

virtualization environments. VM operating system, application and user

data are all stored on a Reduxio storage system.

Desktop Virtualization A highly efficient, high performance storage platform for XenDesktop

virtualization environments. Virtual desktop operating system, application,

and user data are all stored on a Reduxio storage system.

Configuration | 10

Configuration

The following section describes how to set up a Reduxio solution for XenServer using Reduxio Storage

Manager and XenCenter.

Overview

To setup XenServer with Reduxio, the following steps are required:

1. Apply Reduxio required iSCSI and multipathing settings.

2. Enable multipathing on each XenServer.

3. Configure a new network for iSCSI traffic.

4. Provision storage on Reduxio and assign to XenServer hosts.

5. Create a new SR (Storage Repository).

iSCSI Settings

Apply the Reduxio recommended iSCSI settings as documented in the Interoperability section in the

Reduxio Support Portal.

MultipathingReduxio storage supports the Asymmetric Logical Unit Access (ALUA) standard, providing native path

failover and load balancing in XenServer.

Reduxio storage is supported by the DM-Multipath module provided by XenServer.

Networking

Configure a separate network interface that will be used to connect to the Reduxio system. If more than a

single interface is required, repeat the steps below for each NIC.

1. Add a network for iSCSI traffic.

To add a new network in XenCenter:

https://support.reduxio.com/

Configuration | 11

1. Select the pool or server.

2. Select the Networking tab.

3. Click Add Network…

4. Select External Network and click Next.

5. Provide a name, such as iSCSI1, and click Next.

6. Select the relevant NIC, desired VLAN network (keep at one when not using VLAN tagging), and

enter the desired MTU (typically 9000, matching the Reduxio system’s default).

7. Click Finish.

2. Configure IP address for the new network.

From within the Networking tab in XenCenter:

1. Click Configure…

2. Select the network that was added in the previous step.

3. SelectUse these settings… and type the IP address details for this network.

4. Click OK.

Storage Provisioning

XenServer supports the configuration of SRs up to 2 TB. Reduxio volume block size must be 512

bytes.

Configuration | 12

Creating an SR using CLI

Create an LVM SR

To create an LVM-based SR on a Reduxio LUN using the CLI:

1. Identify the target IQN:

# xe sr-probe type=lvmoiscsi device-config:target=10.46.216.11Error code: SR_BACKEND_FAILURE_96Error parameters: , The request is missing or has an incorrect target IQNparameter, <?xml version="1.0" ?><iscsi-target-iqns>

<TGT><Index>0</Index><IPAddress>10.46.216.22</IPAddress><TargetIQN>iqn.2013-12.com.reduxio:af4032f0003a000e</TargetIQN>

</TGT><TGT>

<Index>1</Index><IPAddress>10.64.216.22</IPAddress><TargetIQN>iqn.2013-12.com.reduxio:af4032f0003a000e</TargetIQN>

</TGT><TGT>


</TGT><TGT>


</TGT><TGT>

<Index>4</Index><IPAddress>10.46.216.11</IPAddress><TargetIQN>*</TargetIQN>

</TGT></iscsi-target-iqns>

Configuration | 13

2. Identify the SCSI id for the SR device:

# xe sr-probe type=lvmoiscsi device-config:target=10.46.216.11 device-config:targetIQN=iqn.2013-12.com.reduxio:af4032f0003a000eError code: SR_BACKEND_FAILURE_107Error parameters: , The SCSIid parameter is missing or incorrect, <?xmlversion="1.0" ?><iscsi-target>

<LUN><vendor>REDUXIO</vendor><serial>6f4032f0003a000000000000000001e9</serial><LUNid>1</LUNid><size>2199023255552</size><SCSIid>36f4032f0003a000000000000000001e9</SCSIid>

</LUN></iscsi-target>

3. Create the SR using the parameters identified earlier:

# # xe sr-create name-label="test1" type=lvmoiscsi content-type=userdevice-config:target=10.46.216.11 device-config:port=3260 device-config:targetIQN=iqn.2013-12.com.reduxio:af4032f0003a000e device-config:SCSIid=36f4032f0003a000000000000000001e9edf23112-144d-241c-241e-e707268f8661

Create an ext3 SR

To create an ext-based SR on a Reduxio LUN using the CLI:

iscsiadm --mode discovery -t st -p 10.46.216.11iscsiadm -m node -liscsiadm -m sessionxe sr-create name-label=test1 shared=false device-config:device=/dev/disk/by-id/scsi-36f4032f0003a000000000000000001e9 type=ext content-type=user

Configuration | 14

Deleting an SR using CLI

To delete an SR using the CLI:

Delete an LVM SR

To create an LVM-based SR using the CLI:

xe sr-probe type=lvmoiscsi device-config:target=10.46.216.11xe sr-probe type=lvmoiscsi device-config:target=10.46.216.11 device-config:targetIQN=iqn.2013-12.com.reduxio:af4032f0003a000e

Delete an ext3 SR

To delete an ext-based SR using the CLI:

1. Identify the SR UUID:

# xe sr-list name-label=test1uuid ( RO) : 44c57c66-855c-0ea7-94a3-df839cd75c34

name-label ( RW): test1name-description ( RW):

host ( RO): xen72type ( RO): ext

content-type ( RO): user

2. List the Physical Block Devices (PBDs) for the SR:

# xe sr-list uuid=44c57c66-855c-0ea7-94a3-df839cd75c34 params=PBDsPBDs (SRO) : dc0f4cc2-7a1b-8722-ee6d-19aee68db071

3. Unplug the PBD:

# xe pbd-unplug uuid=dc0f4cc2-7a1b-8722-ee6d-19aee68db071

4. Destroy the SR:

# xe sr-destroy uuid=44c57c66-855c-0ea7-94a3-df839cd75c34

Configuration | 15

Reclaim Space

To reclaim free space using UNMAP:

1. Identify the host UUID:

# xe host-list name-label=xen72uuid ( RO) : 89a3cc14-74da-46ca-863b-03fd2bc33741

name-label ( RW): xen72name-description ( RW): Default install

2. Identify the SR UUID:

# xe sr-list name-label=test1uuid ( RO) : 44c57c66-855c-0ea7-94a3-df839cd75c34

name-label ( RW): test1name-description ( RW):

host ( RO): xen72type ( RO): ext

content-type ( RO): user

3. Reclaim space from the SR:

# xe host-call-plugin plugin=trim host-uuid=89a3cc14-74da-46ca-863b-03fd2bc33741 fn=do_trim args:sr_uuid=edf23112-144d-241c-241e-e707268f8661

Expanding Capacity

SRs can be expanded using the Reduxio volume resize capability.

For more information refer to: How to Online Update the Size of a XenServer iSCSI Storage Repository.

To expand an SR capacity:

1. Expand the volume.

To expand a volume:

https://support.citrix.com/article/CTX126473

Configuration | 16

1. Click Hosts & Vols to open the hosts and volumes screen.

2. Select the volume to expand.

3. Type a new volume size. The size must be larger than the existing volume size.

4. Click OK.

5. The volume is immediately expanded.

2. Identify the SR Universally Unique Identifier (UUID).

Run from the XenServer command-line interface:

[root@xen11 ~]# xe sr-list type=lvmoiscsi name-label=xensmall –minimal385a4089-015a-7bf2-6f68-f05a40d175a9

3. Identify the device used by the SR.


[root@xen11 ~]# pvs | grep 385a4089-015a-7bf2-6f68-f05a40d175a9/dev/mapper/36f4032f0003a00000000000000000024 VG_XenStorage-385a4089-015a-7bf2-6f68-f05a40d175a9 lvm2 a-- 19.99g 19.98g

4. Rescan the target.


[root@xen11 ~]# iscsiadm -m node --targetname iqn.2013-12.com.reduxio:af4032f0003a000e -RRescanning session [sid: 5, target: iqn.2013-12.com.reduxio:af4032f0003a000e,portal: 10.46.216.11,3260]Rescanning session [sid: 6, target: iqn.2013-12.com.reduxio:af4032f0003a000e,portal: 10.64.216.11,3260]Rescanning session [sid: 7, target: iqn.2013-12.com.reduxio:af4032f0003a000e,portal: 10.46.216.22,3260]Rescanning session [sid: 8, target: iqn.2013-12.com.reduxio:af4032f0003a000e,portal: 10.64.216.22,3260]

5. Update the physical volume size.


Configuration | 17

[root@xen11 ~]# pvresize /dev/mapper/36f4032f0003a00000000000000000024pvresize /dev/mapper/36f4032f0003a00000000000000000024: Command not permittedwhile global/metadata_read_only is set.

If the command fails with the metadata_read_only error, as above, run the following

command instead:

[root@xen11 ~]# pvresize /dev/mapper/36f4032f0003a00000000000000000024 --configglobal{metadata_read_only=0}Physical volume "/dev/mapper/36f4032f0003a00000000000000000024" changed1 physical volume(s) resized / 0 physical volume(s) not resized

6. Update the SR size.


[root@xen11 ~]# xe sr-scan uuid=385a4089-015a-7bf2-6f68-f05a40d175a9

BackDating™ | 18

BackDating™

BackDating enables the administrator to revert or clone volumes to any point in time back in the history.

Unlike legacy storage designs, Reduxio operates as a “data recorder” and keeps track of both location—

where is the data stored (LUN and offset)—and time: when the data was written (timestamp).

BackDating is the evolution of snapshots. Snapshots only provide a set of predefined point in time (PITs)

copies per volume, at the cost of complex planning, scheduling, and application-aware backup software.

Backdating replaces all of that with a simple-to-use timeline. It is possible to select any point on this timeline

and clone a volume on its basis.

BackDating enables the XenServer administrator to recover VMs and SRs from any point in time in the past.

Concepts

History Timeline

A history timeline can be thought of as a continuous timeline of seconds from the creation of a volume to the

current time, as seen in the figure below.

History Timeline

In such a timeline, it would have been possible to keep the entire history of a volume, such that it is

recoverable to every second in the pas—from the current time back to the volume’s creation time. Typically,

however, as data ages, its history becomes less relevant. The volume timeline is therefore designed with

multiple granularity levels of history defined by a policy. The most recent part of history still maintains a

continuous timeline of seconds; however, moving towards the past, there are portions when only minutes,

hours, days, and weeks are kept. Each volume is assigned to a single history policy that dictates its history.

BackDating™ | 19

Bookmarks

Bookmarks are user-initiated labels for specific time points in a volume that have significance to the user.

For example, a bookmark can be created for a certain application volume before a major change, such as a

service pack update or a large data processing batch job. These bookmarks would enable the administrator

to identify these times more easily, and recover from failures by cloning or reverting volumes to the

bookmarked time.

History is deleted according to the history policies. However, bookmarks can be used to guarantee that

certain timestamps will not be deleted. For example, use a bookmark tomaintain a baseline version of a

database. Database clones can be created using the bookmark, without the risk of the baseline version

being deleted from the system. All the data blocks required for its timestamp remain until the bookmark

itself is deleted.

There are two types of bookmarks:

Automatic This type of bookmark is automatically deleted based on the history policy assigned

to the volume.

For example, a volume is configured for storing a database. The default policy is

configured. An automatic bookmark is then created for a database backup.

This bookmark will be automatically deleted after the maximum retention level is

reached for this volume. For example, when using the Default-Apps policy,

automatic bookmarks will be deleted after one year.

Manual This type of bookmark is kept by the system until it is manually deleted. This is

especially useful for keeping important time points from being deleted accidentally.

However, to avoid a full system state, manual bookmarks should eventually be

deleted.

BackDating™ | 20

Clones

Clones provide an advanced functionality that is highly beneficial to various recovery, testing, and

development use cases.

Clones are Writeable and

Independent

A cloned volume is 100% equivalent to the volume it based on at the

chosen timestamp. However, the clone and the source volume are

entirely independent from each other. The source volume can be deleted

without affecting its clone or clones. Clones are standard read/write

volumes. This enables the administrator to clone a certain application and

keep running from the clone.

One-to-Many A single volume can be cloned tomany volumes. Note that the clones are

similar to other volumes and are accounted together towards the

maximum number of volumes.

For example, if the maximum number of volumes is 1,000, there can be a

single volume and 999 clones.

Multi-Level Cascading Cloned volumes can be recursively cloned for versioning purposes. For

example, vol1 can be cloned to vol2, which can then be cloned to

vol3.

Automatic Consistency Data is consistent across volumes in every point in the timeline. This

provides inherent support for consistency groups. As long as a set of

related volumes maintains the same timestamps (by configuring the

same or a similar history policy), reverting or cloning volumes to the same

timestamps across the volumes will provide a consistent view.

For example, db1 and log1 volumes are used to store a database’s data

and log files respectively. When cloned or reverted to the same

timestamp, the resulting volumes will be consistent to that timestamp.

BackDating™ | 21

Recovering Data

Volumes can be reverted or cloned from any point-in-time in the history timeline of a volume:

Clone Create a new volume that is based on another volume from a selected timestamp.

For example, consider the following timeline:

Jan 19, 2015 9:34:00am: volume db1 created.

Jan 19, 2015 10:05:00am: volume db1_clone created, based on db1, at timestamp 9:55:04am.

The cloned volume db1_clone will contain the contents of db1 as it was in 9:55:04am.

Concurrently with volume db1_clone, volume db1 continues to function as before—including all

updates it received since the moment of the cloning.

Revert Revert a volume to a selected timestamp.

The volume contents will be changed in-place; any changes beyond the

timestamp will be lost.

For example, consider the following timeline:

Jan 19, 2015 9:34:00am: volume db1 created.

Jan 19, 2015 10:05:00am: volume db1 is reverted to timestamp 9:55:04am.

All changes beyond 9:55:04am are lost.

A volume must be dismounted from the host before a revert operation, as the

host may contain cache information or file system metadata not yet committed

to storage, which may conflict with the reverted volume. After revert is

completed, the volume can be safely remounted.

Data Recovery

Recovering SRs

SRs can be recovered back to any second in the past using BackDating. XenServer does not provide out-of-

the-box support for resignaturing duplicate SRs, so the most straightforward recovery method is to detach

the original SR, and then reconnect the recovered SR.

SRs can be recovered in one of the following methods:

• Clone the SR: Create a clone of the original SR from a past timestamp, power off all VMs running on the

SR, detach it, connect the clone SR instead, and power on all VMs again.

BackDating™ | 22

• Revert the SR: Power off all VMs running on the original SR, detach it, revert the volume of the original

SR to a past timestamp, connect the reverted SR, and power on all VMs again.

Clone and Revert

To clone a volume using Reduxio Storage Manager:

1. Click BackDating from the icon bar.

2. Drag and drop the volume to be cloned to the circular area marked with DRAG VOLUME HERE.

3. If a specific time is required select it using the clock controls. Any timestamp from the available

history can be selected. The time selection is performed by entering the desired time and

selecting AM/PM and the date. It is also possible to use the keyboard arrow keys or scroll the

mouse tomove the time and date forward or backwards. Click SELECT to select the timestamp.

4. Modify the default clone name in the CLONE NAME field.

5. Select the Assign clone to same hosts checkbox to automatically assign the clone to the same

hosts or hostgroup that the original volume was assigned to.

6. Click CLONE on the right side.

7. Modify the default clone name if desired and click OK to clone the volume.

To revert a volume using Reduxio Storage Manager:

Prerequisites: The volume must be taken offline in all hosts accessing it before it is

reverted. This is required in order to maintain data integrity.

BackDating™ | 23







4. Click REVERT on the right side.

5. Click Yes to confirm the revert.

To clone or revert multiple volumes consistently using Reduxio Storage Manager:







4. Click either CLONE or REVERT on the right side as needed.

5. Repeat steps 2 to 4 for the other volumes, using the exact same timestamp. The resulting

volumes or cloned volumes will be consistent between each other to that timestamp.

Following the clone/revert operation, assign the resulting volume clone to a host, typically the same

one assigned to the original volume.

Recover an SR using Cloning

To recover an entire SR using a clone:

1. Identify the SR volume.

Identify the volume in the Reduxio Storage Manager. If needed, the WWID of the volume backing up the

BackDating™ | 24

SR can be identified in XenCenter:

1. Under Infrastructure, select the SR.

2. In the General tab, review the SCSI ID field.

2. Clone the SR volume.

To clone the SR volume using Reduxio Storage Manager:


2. Drag and drop the volume to be cloned to the circular area marked with

DRAG VOLUME HERE.




mouse tomove the time and date forward or backwards. Click SELECT to select the

timestamp.

4. Modify the default clone name in the CLONE NAME field.

5. Select the Assign clone to same hosts checkbox to automatically assign the clone to the

same hosts or hostgroup that the original volume was assigned to.

6. Click CLONE on the right side.

7. Modify the default clone name if desired and click OK to clone the volume.

3. Power off all VMs.

In XenCenter:

1. Select the VMs (CTRL-click).

2. Right-click one of the selected VMs, then select Shut Down (or Force Shut Down if required).

BackDating™ | 25

4. Detach SR.

In XenCenter:

1. Right-click the SR, then click Detach…

2. Click Yes to detach the SR.

3. Right-click the SR, then click Forget.

4. Click Yes to confirm. The SR will be removed from the inventory.

5. Unassign SR.

In Reduxio Storage Manager:

1. Click HOSTS & VOLUMES in the icon bar.

2. Select the original SR volume.

3. Hover over the host/hostgroup within the volume’s panel, then click UNASSIGN.

6. Assign the clone volume to the XenServer pool.

To assign the clone volume to the XenServer pool’s host group using Reduxio Storage Manager:

1. Select the XenServer pool’s host group.

2. Within the host group panel, select the VOLUMES tab.

3. Drag and drop the clone volume to the drop zone below the tab buttons.

7. Identify Reduxio iSCSI IP addresses.

To locate the data interface IP addresses using Reduxio Storage Manager:

BackDating™ | 26

1. Click the Settings icon from the icon bar to open the Settings screen.

2. From the left navigation bar, click NETWORK.

3. Select each of the virtual networks.

4. Two iSCSI IP addresses are listed in the CONTROLLER 1 & 2, PORT 1 & 2 fields. Only virtual

networks that have the USE FOR ISCSI TARGET checkbox selected can be accessed by the

XenServer servers.

8. Create a new SR.

To create the SR using XenCenter:

1. Select the pool.

2. Select the Storage tab.

3. Click New SR…

4. Select iSCSI and click Next>.

5. Type a name (typically the same as the Reduxio volume name) and click Next>.

6. Type one of the Reduxio system’s iSCSI IP addresses in the Target host name/IP address

field.

BackDating™ | 27

7. Click Scan Target Host.

8. The Reduxio system iSCSI IP addresses are discovered and listed in the Target IQN drop-down

list.

9. Select the clone LUNWWID from the Target LUN drop-down list.

10. Click Finish.

11. The clone SR will be detected and the following message will appear:

12. Click Attach SR to confirm the attachment of the clone SR.

9. Power on all VMs.

In XenCenter:


2. Right-click one of the selected VMs, then click Start.

Recover a SR using Revert

To recover an entire SR using revert:

1. Power off all VMs.

In XenCenter:

BackDating™ | 28

1. Select the VMs (CTRL-click) running on the original SR.

2. Right-click one of the selected VMs, then select Shut Down (or Force Shut Down if required).

2. Identify the SR volume.

Identify the volume in the Reduxio Storage Manager. If needed, the WWID of the volume backing up the

SR can be identified in XenCenter:

1. Under Infrastructure, select the SR.

2. In the General tab, review the SCSI ID field.

3. Detach SR.

In XenCenter:

1. Right-click the SR, then selectDetach…

2. Click Yes to detach the SR.

3. Right-click the SR, then select Forget.

4. Click Yes to confirm. The SR will be removed from the inventory.

4. Revert the SR volume.

To revert the SR volume using Reduxio Storage Manager:

Prerequisites: The volume must be taken offline in all hosts accessing it before it is

reverted. This is required in order to maintain data integrity.

BackDating™ | 29


2. Drag and drop the volume to be cloned to the circular area marked with

DRAG VOLUME HERE.




mouse tomove the time and date forward or backwards. Click SELECT to select the

timestamp.

4. Click REVERT on the right side.

5. Click Yes to confirm the revert.

5. Connect to the reverted SR.

To connect the reverted SR using XenCenter:

1. Select the pool.

2. Select the Storage tab.

3. Click New SR…

4. Select iSCSI and click Next>.

BackDating™ | 30

5. Type a name (typically the same as the Reduxio volume name) and click Next>.

6. Type one of the Reduxio system’s iSCSI IP addresses in the Target host name/IP address

field.

7. Click Scan Target Host.

8. The Reduxio system iSCSI IP addresses are discovered and listed in the Target IQN drop-down

list.

9. Select the reverted LUNWWID from the Target LUN drop-down list.

10. Click Finish.

11. The reverted SR will be detected and the following message will appear:

12. Click Attach SR to confirm the attachment of the reverted SR.

6. Power on all VMs.

In XenCenter:


2. Right-click one of the selected VMs, then click Start.

Troubleshooting | 31

Troubleshooting

Log File Locations

Various logs are maintained which can be used to diagnose problems in a XenServer environment:

XenCenter logs:

C:\Users\<username>\AppData\Roaming\Citrix\XenCenter\logs

XenServer logs:

/var/log/xensource.log/var/log/xenstored-access.log/var/log/xenstored.log/var/log/xen/hypervisor.log

Common Problems

Multipathing Problems

To diagnose the multipathing configuration and status use the following commands:

mpathutil listmpathutil status

For more information, refer to the following Citrix documentation:

• CTX118791 - Multipathing Overview for XenServer 6.x

• CTX121708 - How to Configure High Availability Feature in XenServer

https://support.citrix.com/article/CTX118791

http://support.citrix.com/article/CTX121708

Troubleshooting | 32

VM creation fails with “The attempt to create a VDI failed”

VM startup fails with “The SR failed to complete the operation”

Errors

Jul 22 00:40:19 localhost xapi: [error|localhost|756 ||backtrace] VDI.createD:760528a08c78 failed with exception Storage_interface.Backend_error(_)Jul 22 00:40:19 localhost xapi: [error|localhost|756 ||backtrace] Raised Storage_interface.Backend_error(_)Jul 22 00:40:19 localhost xapi: [error|localhost|756 ||backtrace] 1/1 xapi @localhost Raised at file (Thread 756 has no backtrace table. Was with_backtracescalled?, line 0Jul 22 00:40:19 localhost xapi: [error|localhost|756 ||backtrace]Jul 22 00:40:19 localhost xapi: [debug|localhost|755 |Async.VDI.createR:f62296c367e9|xapi] Unmarking SR after VDI.create (task=OpaqueRef:f62296c3-67e9-e956-aec4-c4b03ec57d66)Jul 22 00:40:19 localhost xapi: [error|localhost|755 ||backtrace] Async.VDI.createR:f62296c367e9 failed with exception Server_error(SR_BACKEND_FAILURE_79, [ ; VDIInvalid size [opterr=VDI size cannot exceed 2093051 MB]; ])Jul 22 00:40:19 localhost xapi: [error|localhost|755 ||backtrace] Raised Server_error(SR_BACKEND_FAILURE_79, [ ; VDI Invalid size [opterr=VDI size cannot exceed2093051 MB]; ])

Description

You cannot create an SR greater than 2 TB in size or use Reduxio volumes with blocksize of 4096 bytes.

Solution

1. Delete all SRs larger than 2TB.2. Create new SRs up to 2TB with a block size of 512 bytes.

Conclusion | 33

Conclusion

Reduxio storage solutions are built using a new, innovative storage operating system. Reduxio TimeOS was

designed from scratch to address the current storage challenges by leveraging the latest advances in

processing power and high-speed networks.

The Reduxio HX Series, based on TimeOS, offers breakthroughs in efficiency, performance, and unique

data management capabilities far exceeding anything in the market today.

Reduxio storage solutions offer tremendous value to existing and new Citrix XenServer implementations.

Reduxio storage provides a new architecture, which is highly optimized for virtualization environments.

References | 34

References

Reduxio Documentation

• Reduxio TimeOS™ v3.4 Administration Guide.

Citrix Documentation

• Citrix Support Knowledge Center - XenServer

https://support.citrix.com/en/products/xenserver

Reduxio Solution for Citrix® XenServer 7 · |4 TableofContents Introduction 6 SolutionArchitecture...

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