Notes on CSV backup and restore
The Windows Server 2008 R2 added a new feature for Hyper-V called Cluster Shared Volumes (CSV). CSV allows multiple virtual machines to share volumes (disk LUNs). CSV also allows live migration of a running virtual machine from one Hyper-V server to another without user interruption.
Multiple virtual machines can be created on a single cluster-shared volume (CSV) and owned by different nodes. (Hyper-V servers are configured as nodes in the cluster.) All nodes can access the CSV simultaneously.
NetBackup can back up the virtual machines that are configured in cluster-shared volumes.
Note the following:
During the backup, the cluster-shared volume (CSV) enters the online state ("Backup in progress, Redirected access"). The cluster node that performs the backup becomes the owner of the CSV.
On Windows versions before 2012, multiple nodes cannot back up a CSV simultaneously. When a node backs up a virtual machine on a CSV, the attempt by another node to back up the same virtual machine fails.
Note:
On Windows server 2012, cluster nodes can back up the same CSV simultaneously.
For Windows versions before 2012: You can use the option in the policy to adjust how long NetBackup waits for another backup of the same CSV to complete.
A single node containing two virtual machines can back up both virtual machines simultaneously, even if they use the same CSV. As long as both virtual machines reside on the same node, simultaneous backups are allowed.
For Windows Server 2008 and 2008 R2: If a VM is on a CSV, restoring the VM fails if the CSV is a reparse point that is specified as the restore destination. NetBackup may incorrectly assume that the restore destination is not large enough to contain the VM, and the restore does not start.
For a successful backup of a virtual machine on a CSV, the virtual machine must use CSV volumes only. If a local disk on the Hyper-V server (not a CSV volume) is added to the virtual machine, the backup fails with status 156.
Reconfigure the virtual machine to use CSV volumes only, and retry the backup.