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Any form of reproduction of the contents or parts of this manual is allowed only with the express written permission from SEP AG. When compiling and designing user documentation SEP AG uses great diligence and attempts to deliver accurate and correct information. However, SEP AG cannot issue a guarantee for the contents of this manual.

Introduction

The SEP sesam extension for Citrix XenServer provides hot (online) and cold (offline) backups of Virtual Machines (VMs) running on a Citrix XenServer. Consistent backup is achieved by creating a snapshot of the virtual machine. After creation, the snapshot is exported to a SEP sesam backup medium. VSS writers on Windows VMs are notified before snapshot creation so all VSS aware applications like MS-SQL are brought into a consistent state.

System Requirements

• Citrix XenServer >= 5.5
• SEP sesam server >= 4.0.2.13
• Citrix XEN backup client is included in all SEP sesam packages >= 4.0.2.13

On XenServer

• Nothing has to be installed on the XEN server side.

On a datamover

• Any other SEP Sesam server or SEP Sesam client can act as datamover.

Configuration in the SEP sesam GUI

Configure XenServer in the SEP sesam GUI as client. Choose Citrix XenServer as operating system.

The Username, Password and Data Mover for logging onto the XenServer can be entered in the tab Citrix XenServer. The data mover must be the hostname of the SEP Sesam Backupserver or a non-"Citrix XEN" client.

Backup

Backup of the VM's and XEN Templates

Create a new backup task in the SEP sesam GUI with task type Citrix XenServer. As backup source specify the display name of the virtual machine.

The Virtual Machine can be selected with the client file system browser under Citrix XenServer.

You can also get the name from XEN Center or on the XEN Server by executing command:

Attention: Only ONE VM can be saved by one backup task.

The backup is done online. If XenServer tools are installed on VM VSS-Writers are executed before making the snapshot.

Meta data backup

Create a new backup task for the XEN Master with task type Citrix XenServer. As backup source type in "meta-data". Citrix recommends that you frequently perform this backup task at minimum once per day to recover from possible server and / or software failure. This backup includes the XEN Server pool database and the needed meta data of the pool.

Host data backup

Create a new backup task for each XEN Host with task type Citrix XenServer. As backup source type in "host-backup". This backup is a filebackup of the XEN Hypervisor without the VM's.

Restore

The restore is quite similar to a regular file system restore.

There are 2 different restore options:

with overwrite

the existing VM is destroyed and the backup is imported. The MAC address is the same as during backup.

without overwrite

A new VM name has to be specified as target. The backup is imported without any effect on the running VM. The MAC address of a restored VM is newly created.

Restore options

Recover after restore

Registers the VM after restore on XenServer and with it in XenCenter

Recover and online

Registers and starts the VM and brings it online

You must have a default storage repository defined, otherwise the restore will fail.

File System Option

SEPsesam license for Citrix Xen Server includes a Client backup license for every licensed VM seat to do a file level backup from this VM. To do this, a normal Sesam client has to be installed in the VM and the client has to be configured over GUI.

https connection

SEP sesam commonly uses http to transfer data from XenServer to SEP sesam server for reasons of speed. Backups over https can cause up to 98 % CPU load on XenServer. The use of https can be forced by entering the following option under 'task->properties->backup options:

Troubleshooting

• Some errors are not reported in detail by XEN API. More information can be found in XenServer in /var/log directory.

• In some pool configurations all pool members must have their management interface listed in dns.

• If the settings below don't agree asynchronous routing and connection drops and/or 3 second or 80 second delays opening sockets may occour. This is very similar to having 2 network cards configured with ipv4 to the same subnet and connected to the same switch.

• If you use Cisco Switches and you have configured (Citrix Unsupported) lacp bonding 802.3ad it is very important that both sides agree on the balancing type. The linux default is layer2 and the Cisco default is layer3+4.

• Check the bonding mode on the host with cat /proc/net/bond/bond* for Bonding Mode: IEEE 802.3ad Dynamic link aggregation

Transmit Hash Policy: layer2 (0) or Transmit Hash Policy: layer3+4 (1).

• Users have reported that this command and a reboot solves the problem but we cannot formally recommend it due to the untested and unsupported status:

xe pif-param-set uuid=${UUID_OF_BOND_PIF} other-config:bond-xmit_hash_policy=1

• In the common situation where 802.1ad with xmit_hash_policy=1 and STP are in use multiple settings need to be adjusted on the Cisco side according to this document: http://support.citrix.com/article/CTX123158

• Most other network related performance and reliability issues can be resolved with http://support.citrix.com/article/CTX123158

• In some situations when using thin storage repositories an sr rescan is necessary to re-detect free space before a backup or restore ( This feature will be automated soon )

Further Links/Literature