You may know that HP and Microsoft have formed a virtualisation alliance around Hyper-V. One of HP’s key pieces in the puzzle the the iSCSI SAN formerly known as LeftHand, the P4000 series.
Cluster Shared Volume (CSV) can be backed up using a software VSS provider (i.e. Windows VSS) but this is slow. When using DPM 2010, it’s recommended to use serialised backups. If your hardware vendor support it, you can use their hardware VSS provider to take a snapshot in the SAN and then DPM (or whatever backup product) will use that feature for the backup.
Now back to the P4000. Up until recently, the HP supplied DSM for MPIO was version 8.5. The SAN/iQ software on the P4000 was also at 8.5. Lots of people were using the 8.5 hardware VSS provider in the SAN to backup CSVs. It seems that this was unsupported. by HP (nothing to do with MS). In fact, it can even cause disk deadlock in a Hyper-V cluster, and lead to 0x0000009E blue screens of death (BSOD) on cluster hosts. And that’s just the start of it!
HP did release DSM 9.0 and SAN/iQ 9.0 recently for the P4000. These add support for using the hardware VSS provider for backing up a CSV.
So the SAN/iQ 9.0 release docs say that previous versions of SAN/iQ supported CSVs. However, the Application Snashot Feature (hardware VSS provider/backup application) of the 8.5 release could not support quiecsed snapshots of CSVs. In other words, it wasn’t supported to use DPM (or anything else) to perform a storage/host level backup of LeftHand with SAN/iQ 8.5 using the HP hardware VSS provider. It is supported with v9.0.