VSS Quiesced Snapshot fails on virtual machine with independent disks

Products

• VMware vSphere ESXi

Issue/Introduction

Symptoms:
If a VM has one or more disks set to "independent-persistent" snapshot mode (including "independent-eraseonrevert" for PMem disks), and the VM has VSS configured ("Volume Shadow Copy Service"), quiesced snapshot creation may fail with a "quiescing error". The specific VMware error message will be:
"An error occurred while quiescing the virtual machine. See the virtual machine's event log for details."

There will also be a "Volume Shadow Copy Service" error in the guest Windows Event Log, containing the message "A critical volume selected for backup exists on a disk which cannot be backed up by ASR."

Cause

Microsoft VSS code in the Guest OS may expect all volumes to be included in the VSS quiescing process, but independent disks by definition are not part of a snapshot.

For more information, see Change Disk Mode to Exclude Virtual Disks from Snapshots

Resolution

VSS quiescing should be disabled for a VM experiencing this issue. For more information, see Disabling VSS quiesced application based snapshots in virtual machine (2146204)