We have a 3 node Server 2012 R2 Hyper-V Cluster and we use DPM for backing them up. Today all the guests went into a paused state with Failover Cluster Manager reporting there was less than 1GB free on a 7TB CSV. Checking the underlying SAN showed there was more than 2TB free space. After manually changing the CSV owner from one Hyper-V node to another in Failover Cluster Manager it suddenly started reporting the free space as being 2.3TB and I could then resume all the VMs.
I've read this KB https://support.microsoft.com/en-us/kb/2813630 for a hot fix which describes a similar issue but it's for Server 2012 so I assume this particular issue has been fixed in Server 2012 R2.
Any one seen this happen on their R2 cluster?
For the record we have Offloaded Data Transfer disabled as our SAN doesn't support it.