VSS snapshot of a Hyper-V virtual machine on SFW storage does not work from NetBackup

This issue occurs while taking VSS-aware snapshot or backup of a Hyper-V virtual machine using NetBackup and the virtual machine's VHD is on a dynamic volume belonging to an SFW cluster disk group.

During the VSS snapshot process, VSS service on the host machine (hypervisor) internally takes a snapshot of the VHDs belonging to the guest virtual machine (OS VHD as well as data VHDs) and exposes these snapshots to the host machine. As a result, we can see disk arrivals (snapshots of the guest VHDs) and the corresponding volume arrivals (partitions on the guest VHDs) on the host machine.

When SFW is installed, auto-mounting is disabled by default. But, for a successful backup of a Hyper-V virtual machine (guest), VSS on the host machine expects the arrived partitions to be automatically mounted. When VSS doesn't find these partitions to be mounted, it fails the backup operation of the guest virtual machine and NetBackup displays error with the code 156. (3342470)

Workaround: There is no workaround for this issue.