Agentless backup of Hyper-V VM from a Windows Hyper-V 2012 R2 Host fails with the following errors:-
Failed to initialize the Hyper-V environment.
Failed to prepare for backup of the virtual machine.
|Hyper-V VMMS Admin Event Log|
One or more shareable VHDs are attached to virtual machine 'TESTVM'. Back up programs that use the Hyper-V VSS writer cannot back up volumes that are backed by VHDs which are potentially attached to other VMs. To avoid potential data loss, use another method to back up the data on the shareable VHD. If you restore the data on this virtual machine, make sure to check the data of shareable VHD for integrity. (Virtual machine ID xxxxxxx-X1B3-1234-A1B2-xxxxxxxxxx)
This limitation is caused by Hyper-V, and not Arcserve UDP. Any agentless solution will have this limitation.
From Windows 2012, there is a new “shared VHD” feature of Hyper-V, which allows you to share the VHD(X) file among multiple VMs. (For more information about this feature, refer to the following blog: Shared VHDX Files - My Favorite New Feature in Windows Server 2012 R2). However, Hyper-V VSS Writer does not support this new feature. As a result, a Hyper-V agentless backup to a VM containing this “shared VHD” feature will fail. In order to back up this type of VM, you will need to run an agent backup by installing Arcserve UDP Agent for Windows on the VM.