5120
Microsoft-Windows-FailoverClustering
Cluster Shared Volume 'Volume2' ('ClusterStorage Volume 2') is no longer available on this node because of 'STATUS_CLUSTER_CSV_AUTO_PAUSE_ERROR(c0130021)'. All I/O will temporarily be queued until a path to the volume is reestablished.
You may see this error when trying to backup Hyper-V hosts which use Cluster Shared Volumes (CSVs) on server 2012.