Merge Snapshots to permit fixed-sized VHD RRS feed

  • Question

  • I have a critically important Hyper-V VM that I need to have backed up regularly (while it's hot). MS Support has been unable to help here (after over a month) but recently I read a whitepaper that says the VMs have to have fixed-sized drives to be backed up by Windows Backup. So, each of my VMs (for one reason or another) have snapshots and variable-sized drives. In one VM I have a single snapshot, but in others they are several deep. I now learn that this is also causing some of my performance problems--which is another reason to eliminate the snapshots.

    Question: How do I SAFELY merge these snapshots into the primary VM file? Some say to "delete" the snapshot but to me that means roll it back. That's NOT what I want. I want the new VM to be in the current "snapshot" state when it's done with the merge.

    Next, I assume that once the merge is complete and all of the snapshots are gone, I can safely reconfigure to a fixed disk size and retry the backups.

    UPDATE: I have been able to successfully backup the system by increasing the timeout used to create the backup image snapshots. I still need to be able to safely merge the snapshots and change to fixed-sized disks for performance reasons.

    William Vaughn
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    Monday, August 1, 2011 4:40 PM

All replies

  • The terminology that Hyper-V uses can be a bit confussing, Delete Snapshot and Delete Snapshot Subtree will merge the snapshot back into the base vhd.

    The Apply from the snapshot right-click menu is for rolling back to before the snapshot, the Revert from the action menu is also for rolling back to before the snapshot.

    Export is the safest way to save the virtual machine before you attemp a delete snapshot or delete snapshot subtree.

    After merging the snapshot you should be able to convert the vhd to fixed size, but be aware I think they will all try to convert to 127GB drives, since that is the default for dynamic.

    Bill Chesnut | BizTalk Server MVP | Mexia Consulting | Melbourne Australia
    Please indicate "Mark as Answer" if this post has answered the question.
    Monday, August 1, 2011 10:56 PM