Two AVHD files point to parent, how to merge?

Question

I have a VHDX file with two AVHD differencing files, but they are not chained. Both differencing files point straight back to the parent. I've shutdown the guest for over 24 hours and no merge has taken place. How do I get the differencing files to merge without losing data?

Thanks!
Joe

Answer 1

I was unable to resolve the issue and had to restore from the previous day's backup, resulting in a day's loss of data.
Joe

Answer 2

Hi,

Do you know how the differencing disks appear, does the avhd differecing disks created by checkpoints?

If the avhd file is created by checkpoints, can we see the checkpoints tree in the Hyper V manager? If yes, please provide a screenshot of it.

"Both differencing files point straight back to the parent" this is strange, if it is checkpoints differencing avhd, there should only one avhd file point to the parent disk.

Please also check if you are using differencing disk to create the VM, like the method in the below article:

https://www.nakivo.com/blog/use-hyper-v-differencing-disks-complete-guide/

(Please note: Information posted in the given link is hosted by a third party. Microsoft does not guarantee the accuracy and effectiveness of information.)

Thanks for your time!
Best Regards,
Anne

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Answer 3

Anne,
Thanks for the reply. When I created this case the only checkpoint listed in Hyper-V Manager was 'Now'. Today when I check there is another checkpoint from Veeam. I've included the two inspection windows for the two AVHD files showing they both point to the parent. Any thoughts are greatly appreciated.
Joe

Answer 4

Hi,

According to your screenshot, it is a recovery checkpoint created by the backup tool, in your case, they are created by Veeam backup tool. Normally, recovery checkpoint will be deleted automatically after backup. If not, please try to merge them manually.

Manually Merge .avhd to .vhd in Hyper-V

https://social.technet.microsoft.com/wiki/contents/articles/6257.manually-merge-avhd-to-vhd-in-hyper-v.aspx

You can't delete a recovery checkpoint for a virtual machine in Data Protection Manager

https://learn.microsoft.com/en-us/troubleshoot/windows-server/virtualization/cannot-delete-recovery-checkpoint-vm

Thanks for your time!
Best Regards,
Anne

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Answer 5

Anne,
I'm working on this but I do plan to move this VM to another server soon. Can I do a live migration with AVHD files existing? Will the live migration merge the files?

Thanks,
Joe