WSB issues with Hyper-V guests.
Host is Windows Server 2012 R2, with all current updates installed. Only Hyper-V role.
There are 2 guests, call them guest A and guest B, which both have up to date integration components. Guests are both running Windows Server.
WSB jobs always reports "Completed with warnings". Configured for full server backup.
Guest A backs up online with no issues.
Guest B goes into saved state because it contains dynamic disks. (Guest B runs DPM, therefore by design we have no choice re dynamic disks).
Q 1:
"Pass-through and iSCSI disks are not visible to the host operating system and therefore not backed up by the Hyper-V VSS writer. Backups of these volumes must be done entirely within the VM."
Guest B uses iSCSI to connect to a NAS and that is where the dynamic disks reside.Considering the above statement, I was hoping the VM could be backed up online, as the dynamic disks are apparently not visible to the host.
Is there any tweak to ignore the dynamic disks so that the guest can be backed up online? Note we’re not trying to include the iSCSI volumes in the guest backup. The point is if the dynamic disks are not visible to the host because they’re iSCSI-based then why should this prevent an online backup of the guest?
Q 2:
I am trying to understand if the saved state backup is the reason the backup job is 'completing with warnings', or if we have a separate problem.
When the backup runs it backs up the physical volume containing the guest B VHDX, and it test restores successfully.
But the item in WSB named "guestb(Offline)", reports status "Backup failed to complete". It acknowledges that it is trying to do an offline backup since it says "(Offline)", so the dynamic disks should not be an issue being on offline backup.
I have tried disabling "Backup (volume checkpoint)" integration service component in the guest settings but it still fails with the same error.
When the same guest was running on Windows Server 2012 (R1) with Hyper-V this was not an issue. But since moving the guest to a new server running R2 we get "Backup failed to complete" and "Completed with warnings".
I have observed a similar issue with another customer using R2. If guest is shutdown i.e. Off, WSB reports the same error messages as above. Turn the VM back on, and it completes an online backup with no issues reported. It seems silly that we cannot get a clean backup result just because a guest is shutdown. Is this correct?