The host in question is a Windows Server 2008 R2 Datacenter edition host with 64GB of RAM set up as a dedicated Hyper-V server with a 2TB backing store attached via a PERC 5/e controller to a Dell MD1000. The server is a Dell Poweredge R900 Quad, quad-core.
Using Windows Server Backup it attempts to put some non-integration services available guests into saved state and use Volume Shadow Snapshots on the rest.
This takes at least 9min to do as there are at present 35 live guests, as a result the Volume Shadow Snapshot times out and the backup fails.
Is there a way to extend the timeout of Windows Server Backup to say 20 min for the volume shadow creation? Or is there a way to programatically put the guests into a saved state, run windows server backup and then bring back only the guests that were put into a saved state after the snapshot completes? This was how I back up our existing Virtual Server instances.