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GreggHughes-3883 avatar image
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GreggHughes-3883 asked YuhanDeng-MSFT commented

Orphaned snapshots - new user, old question

Good evening, all!

Coming back to the question of orphaned snapshots -

My customer has a Window server 2003 VM (yep, was updated, only there for archival purposes) running in a Windows 2012 R2 Hyper-V cluster. I tried to migrate this VM to a new 2019 Hyper-V host; migration failed immediately at the source, throwing Error 21024 - the migration failed.

On closer examination I found that the VM had .avhd and .avhdx disks running, with links to the parent disks. In Hyper-V Manager, there are no checkpoints listed, but I can't edit the disk because the snapshots exist. I've seen conflicting information on fixing this - shut down the VM and it'll cure itself, manual merging the snapshots to the parent disk, exporting the VM, use PowerShell instead of Hyper-V Manager, and other more exotic fixes. I shut down the VM and left it for several hours; the disk sizes didn't change. I copied the existing file structures to another location so they wouldn't be lost as I worked on the existing disks.

So there are three issues here:
1. Is this likely the reason the migration is failing, or do I need to look further for why the migration failed?
2. What's the least risky method to merge these and restore the disk structure to something closer to normal? I'm from a VMware background, so some of the quick fixes will need references.
3. Is there a way to test this using the disk files I copied over to the offline location? Is there more documentation on how VHDx formats work so I can reasonably predict the outcome of one recovery method over another?

Thanks to all for looking!

G



windows-server-hyper-vwindows-server-2012
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YuhanDeng-MSFT avatar image
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YuhanDeng-MSFT answered

Hi Gregg,
For question 1,would you check the event logs and see if there’s anything relevant to your issue?You can use event viewer to see the logs:
119605-image.png
If possible,please provide error codes or event ids so that we‘d determine the problem easier.

For question 2,I would suggest that you merge the avhdx files back to their parent vhdx,for your reference:
https://www.nakivo.com/hyper-v-backup/merge-hyper-v-snapshots-step-step-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.

And for the last question, I did some research but I didn’t find much official documents about it, maybe you can take a look at this:
https://docs.microsoft.com/en-us/windows-server/storage/disk-management/manage-virtual-hard-disks

Thanks for your understanding.
Best Regards,
Danny


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GreggHughes-3883 avatar image
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GreggHughes-3883 answered YuhanDeng-MSFT commented

Good afternoon, Danny!

After following up on your suggestion, I trawled for some more specific error codes. While I didn't find anything specific, I did find a number of older entries that explain the presence of some of the automatic disks - to the point that I couldn't guarantee how the server would look once I merged the snapshots.

So, we're going to restore from backup. I'm pretty certain I can get a functional image from the current mounted VHDx's and make a reference server I can reasonably confidently archive.

Thanks very much for your help!

Gregg

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Hi Gregg,
Thanks for your feedback. If you have any other concern,please feel free to feedback.

Have a nice day!
Best regards,
Danny

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