I'm using the built-in Windows Server Backup on my Hyper-V host (running Server 2012 R2 Standard) to back up a guest VM named SVR2012 (also running Server 2012 R2 Standard).

Several VHDX files are attached to SVR2012. One is larger than my backup drive but does not need to be included in the Hyper-V host's backup. However, I've not been able to figure out how to excluded this VHDX/volume from the backup.

Backup selections on Hyper-V host:

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Since SVR2012's large VHDX is stored on its own separate volume F: on the Hyper-V host, I've tried excluding that volume: enter image description here

However, when I save the backup schedule, this exclusion is missing the next time I edit the schedule.

How can I configure Windows Server Backup to perform an "online" backup of a Hyper-V guest but exclude from the backup one of the guest's volumes/attached VHDX files?

  • Twisty - Did you every figure out a way around this without having to dismount other non-core OS partitions in the VM so Windows Server Backup only backs up the volumes you need it to (or exclude others)? If you have any suggestions or workaround, I'm very interested in hearing about them. Please let me know. . . Thanks!! – Pimp Juice IT Apr 5 '17 at 16:43
  • @ModeratorImpersonator No, I've not found a workaround, although I'm sure that temporarily unmounting the VHDX to exclude from the backup could be done with a simple script (assuming that wouldn't break anything in the VM). – I say Reinstate Monica Apr 5 '17 at 16:54
  • @ModeratorImpersonator The size of your backup on the backup destination will be the size of the VHDX file as it appears on the Hyper-V host, regardless how much data the VHDX contains. I.e., a 100 GB fixed sized VHDX that only contains 5 GB data will consume 100 GB on the backup destination. Same applies to dynamic VHDX files as well. – I say Reinstate Monica Apr 5 '17 at 16:57
  • I should clarify that this applies to backups created with Windows Server Backup, directly from the Hyper-V Host. Backups created in-guest consume space commensurate to the actual data size. – I say Reinstate Monica Apr 5 '17 at 17:08
  • @ModeratorImpersonator Yes, I do full online backups of my VMs and have sized the destination media to be large enough such that all VMs and their max allocated size consume <=80% of the backup destination (the other 20% is for backup versions, i.e. shadow copies). I've stopped doing in-guest backups to fixed VHDXs on the host, which is the backups strategy I had been using that prompted this question. – I say Reinstate Monica Apr 5 '17 at 17:14

Windows Server Backup is a very basic tool. It just backs up whatever is reported by various installed VSS Writers. It's not going to be able to break apart a VM and deal with only parts of it.

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