Subclient Configuration for Citrix Hypervisor (XenServer)

A subclient identifies a group of virtual machines to back up. The subclient also associates the subclient content with a storage policy that identifies where backup data will be stored.

To perform backups using a subclient, you need to assign a new or existing storage policy to the subclient. The storage policy identifies a library that stores backup data.

The default Subclient and User-Defined Subclients

When you create a new Xen virtualization client and instance, a defaultBackupSet and default subclient are created automatically. A default subclient is also created automatically for each backup set you add.

You can create additional user-defined subclients to back up selected virtual machines. Use this approach to provide different policies, options, or backup schedules for different categories of virtual machines.

The original settings for the default subclient include the backslash ( \ ) value (All unprotected VMs) on the Content tab, which means that all virtual machines from the configured XenServers will be backed up if they are not covered by another subclient. A best practice approach is to retain this setting for the default subclient, and to create additional user-defined subclients as needed to manage different groups of virtual machines separately.

Caution: Do not modify the content property for all default subclients. At least one default subclient should have the capability to serve as a catch-all entity for Xen data. If you disable this feature for all default subclients, some data in the Xen pool may not get backed up.

When a virtual machine is included in a user-defined subclient, it is automatically excluded from the default subclient. This exclusion prevents the default subclient from duplicating a backup of any virtual machine. (Duplicate backups still occur if a virtual machine is included in multiple user-defined subclients.)


  • Backup jobs for the default subclient complete successfully if no virtual machines are discovered for the default subclient. To change this behavior, configure the AllowEmptyDefaultSubclient additional setting on the Virtual Server Agent proxy and set the value to false.
  • To enable backup jobs for non-default subclients to complete successfully when no virtual machines are discovered for non-default subclients, configure the AllowEmptySubclient additional setting on the Virtual Server Agent proxy and set the value to true.

Adding and Excluding Virtual Machines

For a new or existing subclient, you can select objects to include, define rules to discover VMs, or define filters to exclude virtual machines.

  • Browsing and selecting virtual machines, hosts, storage repositories, or folders identifies specific targets for backup operations.
  • Automatic discovery rules select virtual machines based on the VM name or pattern, host, operating system group, or DNS host name.
  • Filtering excludes virtual machines or VM disks based on similar criteria.

    You can define filters on a subclient (only applies to that subclient) or on a backup set (applies to all subclients under the backup set).

By combining automatic discovery and filtering, you can precisely target virtual machines to be included for each subclient and provide flexibility for changing virtualization environments.

Related Topics

Last modified: 11/8/2019 3:29:35 PM