A. VSS Backups will be supported with CSV in Server 2008 R2, but remember how CSV works. You have one node in the cluster that is the coordinator node for a volume and the other nodes in the cluster perform direct I/O at a block level.

When you need to create a point-in-time backup of a CSV volume, you must create a stable environment. Conducting backups of a CSV volume requires special considerations and new APIs that backup applications must use to work in a CSV environment. When a backup of a CSV volume is initiated on a Hyper-V Cluster node, that particular CSV volume must be locally mounted on (or moved to) the machine running the backup. In addition, all remote application disk I/O to and from the CSV volume is re-routed over Server Message Block for the duration of the backup, instead of using direct I/O. Backup applications that haven't been modified to use the new VSS API will not be able to safely backup a CSV volume. Microsoft is working with the ISV and independent hardware vendor communities to evangelize the changes required for CSV Backup/Restore. You should verify with your backup vendor that they explicitly support CSV by using the new PrepareVolumeForSnapshotSet API call.

See also:
How do I create a failover cluster in Windows Server 2008?
Is a Windows Server 2003 and Windows Server 2008 mixed-cluster possible?
How can I add disk resources to a Windows Server 2008 cluster from the command line?
How do cluster shared volumes work in Windows Server 2008 R2?

Videos:
How to Manage Failover Clusters in Windows Server 2008
Configure Windows Server 2008 Failover Clustering from the Command Line


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