Using ESVA iscsi-host Storage with Citrix XenServer 5.6: Data Recovery Configurations

Abstract

This application note describes how to use ESVA iSCSI-host storage systems

with Citrix XenServer 5.6, in particular data recovery configurations for

snapshot, volume copy and volume mirror.

Using ESVA iSCSI-host Storage with

Citrix XenServer 5.6:

Data Recovery Configurations

Table of Contents

ESVA (Enterprise Scalable Virtualized Architecture) ... 3

Citrix XenServer ... 4

Set Up Storage Environment Featuring ESVA and Citrix XenServer 5.6 ... 5

Attach ESVA Storage in XenCenter GUI ... 6

Out-of-Band Flush Settings ... 10

Snapshot Rollback... 13

Volume Copy Recovery ... 19

ESVA (Enterprise Scalable Virtualized Architecture)

The Infortrend ESVA (Enterprise Scalable Virtualized Architecture) Series is a

leading storage solution designed for mid-range enterprise SAN. At affordable

prices, it meets mission-critical storage demands for performance, scalability

and reliability with advanced hardware designs and comprehensive data

services. On the innovative Enterprise Scalable Virtualized Architecture, various

features, including storage virtualization, thin provisioning, distributed load

balancing, automated storage tiering, automatic data migration, prioritized

volume accessibility, snapshot and data replication, are consolidated to realize

optimal business benefits. With ESVA systems, users can optimize ROI, simplify

storage infrastructure, and maximize application productivity.

Infortrend is a Citrix Ready partner. Selected storage systems from Infortrend's

ESVA family have been verified as Citrix Ready®. These ESVA systems have

successfully passed a series of tests established by Citrix, and can be trusted to

work effectively with Citrix XenServer in order to optimize performance of

virtualized datacenters.

For more information about Infortrend’s ESVA storage systems, please visit our

website: http://esva.infortrend.com/.

Citrix XenServer

XenServer is a free, enterprise-class, cloud-proven, and open server

virtualization solution that radically reduces datacenter costs by transforming

static and complex IT environments into more dynamic, easy-to-manage virtual

datacenters. It provides advanced management capabilities to integrate and

automate virtual datacenters at a fraction of the cost of other solutions.

XenServer is a complete virtual infrastructure solution that includes a 64-bit

hypervisor with live migration, full management console, and the tools needed to

move applications, desktops, and servers from a physical to a virtual

environment. XenServer allows organizations to create and manage unlimited

servers and virtual machines that can be run safely and securely from a single

management console. Customers that need additional management, availability,

integration, or automation capabilities can simply upgrade to a premium edition

of XenServer to create an enhanced virtual datacenter. The Advanced,

Enterprise, and Platinum Editions of XenServer offer rich management and

automation capabilities that provide full datacenter automation, advanced

integration and management, and key performance features.

For more information about Citrix XenServer, please visit the following website:

http://www.citrix.com/English/ps2/products/product.asp?contentID=683148.

Set Up Storage Environment Featuring ESVA and Citrix

XenServer 5.6

Before starting to use the configurations described in this application note, make

sure your Citrix XenServer and ESVA storage systems are properly installed.

For Citrix XenServer installation of XenServer, please refer to

http://support.citrix.com/article/CTX124889. For installation of ESVA storage

systems, please refer to your ESVA installation guide.

A common topology featuring ESVA storage systems and Citrix XenServer is

shown below. Make sure to install XenServer 5.6 on the host server and

XenCenter 5.6 on the client.

Attach ESVA Storage in XenCenter GUI

To use the ESVA systems in conjunction with Citrix XenServer, the storage first

has to be attached to the Citrix XenCenter GUI. The following includes

instructions to attach ESVA storage.

First, connect to the XenServer:

Go to New Storage in the XenCenter GUI, as shown below:

Choose to add new storage by selecting Software iSCSI listed under Virtual disk

Enter a name and target host IP for the new iSCSI storage, and click on

Discover IQNs.

Choose the target LUN and click Finish.

The new storage information can be found in the XenCenter GUI, as shown

below:

Out-of-Band Flush Settings

Out-of-band flush settings are required to conduct some of the procedures

described in this application note.

Please follow the below description for relevant configurations.

When installing the SANWatch management software, select the Custom mode.

Select Used for out-of-band flush only and click Next.

In the Virtualization Manager of SANWatch, you are able to see the Out-of-band

Click Out-of-band Flush Setting and choose Add to add flush agent.

After completing the settings, you will see relevant information in the flush agent

list.

Snapshot Rollback

Users can create snapshots on ESVA systems via the SANWatch management

suite. Snapshots allow users to perform instant, low-impact backups with

space-efficient differential copies. In the instant of snapshot creation, a

point-in-time data image is taken without disrupting online applications. Based

on the image, data changes will be copied to the snapshot volume when new

writes occur.

For information on creating snapshots in SANWatch, please refer to your ESVA

user manuals.

Snapshots can be rolled back to restore data in the event of logical or physical

errors. When working in a Citrix XenServer environment, several configurations

are required to successfully roll back data, as described below:

If you have already created snapshots and want to roll back data, you must first

detach the relevant virtual disk in XenCenter. This is part of an un-mapping

process that is required for snapshot rollback to ensure that volumes are not

affected by new incoming I/O during the time the snapshot volume is being

rolled back.

Click on the virtual disk in the OS menu and select Detach.

The next step is to un-map the original volume in SANWatch. To do so, go to

Virtualization Manager > Virtual Volume.

Select the host LUN you want to un-map and click Un-map at the bottom of the

page. The un-mapping process will start, and your screen will show the

following.

After the previous step has been completed, start the snapshot rollback in

SANWatch. Select the relevant snapshot from the Snapshot List in SANWatch,

and select Rollback on the menu bar below.

The following screen will appear:

After the rollback is complete, the virtual volume has to be re-mapped to the host.

Go to Virtualization Manager > Virtual Volume. Click on the volume you want to

map and select Host LUN mapping.

Please note that the mapping settings of the volume you un-mapped are not

stored by SANWatch. Therefore, please make sure to record mapping settings

to enable quick re-mapping in the event of snapshot rollback or other events.

After the re-mapping process has been completed, the virtual disk has to be

reattached in XenCenter.

In XenCenter, click on iSCSI virtual disk storage and select Reattach.

Reattach the virtual disk.

Attach the virtual disk in the guest OS by clicking on the OS in the left-side

column.

Volume Copy Recovery

With the volume copy function on ESVA systems, users can create a full copy of

production data in their storage pool. Volume copy allows users to quickly and

easily create multiple disk-based data copies in ESVA storage pools at

minimized performance degradation. Besides rapid recovery, these data copies

can also be used for secondary applications, such as testing, development and

decision support.

For information on how to create a volume copy, please refer to the ESVA user

manuals.

If a source volume fails, the target volume can be identified by XenServer to take

over any operations of the source volume if necessary.

To start the process of mapping the copy volume (target volume), first detach the

existing volume in XenCenter. Click on the OS in the left-side column and select

a virtual disk. Click Detach on the menu that appears.

Continue by clicking on iSCSI virtual disk storage in the left-side column. Detach

the relevant virtual disk storage.

After detaching, go to iSCSI virtual disk storage again, and select Forget.

When this is done, the virtual volume has to be un-mapped in SANWatch. Go to

the Virtual Volume List and select the volume you want to un-map by clicking on

it and selecting Host LUN mapping from the menu.

Un-map the source volume.

The next step is to map the target volume in SANWatch. Go to the Virtual

Volume List and select the target volume. Click on it and choose Host LUN

mapping.

Complete the mapping configurations and click OK.

In XenCenter, click on XenServer in the left-side column and select New

Choose Software iSCSI listed under Virtual disk storage and click Next.

XenCenter will plug the target volume. After completion, the virtual disk will be

shown in the XenCenter GUI, as shown below.

Attach the target volume to the guest OS. We use Windows Server 2008 R2 as

example. Click on the OS in the left-side column, select the virtual disk and click

Volume Mirror Recovery

The ESVA systems also offer volume mirror functionality. The copies created

through volume mirror can be constantly synced with the source, or split as

independent copies. When a RAID-protected volume fatally fails, the copy

constantly synced can be leveraged for quick recovery without any data loss.

Split copies can be used to enhance operational resilience by allowing shared

access of critical information among production and batch applications, such as

testing, data mining, scientific analysis and tape backup. As business needs

require, the split copies can be quickly re-synced with source.

For information on how to create a volume mirror, please refer to the ESVA user

manuals.

If a source volume fails, the target volume can be identified by XenServer to take

over any operations of the source volume, if necessary. Procedures are similar

to the abovementioned steps for volume copy.

To start the process of mapping the copy volume (target volume), first split the

mirror copy in SANWatch.

Go to Virtualization Manager > Data Service > Replication.

The system will split the copies and report when the process is complete.

To start the process of mapping the mirror copy volume (target volume), first

detach the existing volume in XenCenter. Click on the OS in the left-side column

and select a virtual disk. Click Detach.

Continue by clicking on iSCSI virtual disk storage in the left-side column. Detach

the relevant virtual disk storage.

When this is done, the source virtual volume has to be un-mapped in SANWatch.

Go to the Virtual Volume List and select the volume you want to un-map by

clicking on it and selecting Host LUN mapping from the menu.

The next step is to map the target volume in SANWatch. Go to the Virtual

Volume List and select the target volume. Click on it and choose Host LUN

mapping.

In XenCenter, click on XenServer in the left-side column and select New

Storage.

Reattach the virtual disk.

XenCenter will plug the target volume. After completion, the virtual disk will be

shown in the XenCenter GUI, as shown below.

Attach the target volume to the guest OS. We use Windows Server 2008 R2 as

example. Click on the OS in the left-side column, select the virtual disk and click

Attach.