An “interesting” week for Hyper-V/clustering hotfixes, and they didn’t stop. Some more came out yesterday. Test (if you can), wait a few weeks, and then deploy. This one is for when a Physical Disk resource move during the backup of a Cluster Shared Volume (CSV) may cause resource outage.
Symptoms
Consider the following scenario:
- You configure a Windows Server 2012-based Hyper-V failover cluster.
- The VHD or VHDX files reside on a Cluster Shared Volume (CSV).
- Backups of the CSV are performed using software snapshots.
- Physical Disk resource for the CSV is moved to another node in the cluster.
In this scenario, the Physical Disk resource may fail to come online if the backup of the CSV is in progress. As a result, virtual machines that rely on the CSV may crash.
Cause
During a move of the Physical Disk resource, when the Physical Disk resource comes online on the new node it queries Volume Snapshot Service (VSS) to discover the software snapshots associated with that volume. If the move takes place while software snapshot is in progress, VSS may fail to respond or have a long delay to respond. Ultimately, this may cause the Physical Disk resource to either fail to come online or take a long time to come online on the new node. As a result, VMs that have VHD files on the CSV may crash.
A supported hotfix is available from Microsoft.