Hi

We are running a 3 node Hyper-V failover cluster with a CSV stored on a new SAS connected SAN.

Hyper-V hosts run Server 2012 R2 with all current updates and DPM is 2012 R2 and also with latest updates.

The question is whether we should use the hardware VSS provider and let the SAN do hardware based volume snapshots or if we should just use the VSS Null Provider which uses Hyper-V Checkpoint's to make online VM backup's.

We currently have some issues with the hardware VSS provider which seems both slower when having to negotiate and start the backup's and which seems to have issues with the mapped shadow data volumes getting stuck on the hosts. When using the VSS null provider everything works fine.

I read some places that Microsoft stopped relying on hardware VSS providers with DPM 2012 R2 U3 where they introduced the VSS null provider and made it the default provider, so that in fact you need to disable it in registry to use a hardware provider.

But is that the case ? Is it now recommended by Microsoft to use the VSS Nulll provider to backup VM's hosted on CSV's and what would be the benefits and drawbacks compared to hardware based providers.

I fail to find proper information about that.

Thanks for any links or answers that can help shed some light on to this.

Best Regards

Martin

I have had much better success with the VSS Null Provider than I ever had with VSS hardware providers. 

Good info here:  http://blogs.msdn.com/b/virtual_pc_guy/archive/2015/03/09/how-hyper-v-backup-got-better-in-2012-r2-but-now-requires-a-scsi-controller.aspx

Thanks for the link. Very good information about how VM backup's work with the new VSS Null provider service.

I would still like to know more about the benefits and drawbacks compared to Hardware VSS and letting the SAN handle the snapshot's. Why would one choose one over the other except that i experience the same as you, that the VSS Null provider just seems to work much better.