Persistent Reservation and Disk Offline

Hi,

i have 2 nodes Hyper-V Cluster (Windows 2008 R2) that use an hp MSA2324i SAN for CSV Storage, the Cluster is in production since 2010 without any problem.

Without any reboot or interruption, all cluster volumes went off-line.

I found in Cluster.log this error:

ERR   [RES] Physical Disk <XXX>: Failed to preempt reservation, status 170"

I fixed this issue with this command: cluster node [Node Name]/clear:[DiskId]
but i could not find the cause of  this issue and so the problem could happen again.

After checked the MSA Logs, HP support excluded any possible issue on MSA.

anyone know what would have been the cause of this issue?

Thanks.

Emanuele.