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Server 2012 Hyper-V critical issue with vhd - chain of virtual hard disks corrupted - mismatch in  identifiers of parent VHD / differencing disk - Screenshots Attached

Posted on 2013-11-03
Medium Priority
Last Modified: 2014-11-12
( Screenshots Attached ) When spinning up a VM on Server 2012 Hyper-V ... "the chain of virtual hard disks is corrupted" <avhdx identifier>  "there is a mismatch in the identifiers of the parent virtual hard disk and differencing disk". Yes.. THIS is the problem.. HELP!
I have screwed up royally.

I was up for over 24 hours, (while it is not an excuse) and I made  a series of stupid, foolish, mistakes such as I carelessly moved vhdx files off the public vhd/avhdx hyper-v folder without first having a good backup, a recent snapshot, a backup of that verified backup, and then I did it... The biggest most stupid human-me error, that I don't know where it came from, I did it ..I  clicked, and watched helplessly as  the system applying your requested yet brainless change and in slow motion as I clicked 'cut' instead of 'copy' and watched 4 months of avhdx files begin their escape from the host to a third server in my rack. "Green bar applying change to your HVD.. Warning".. It was too late.. stupid me, stupid me, stupid me!

Yes.. for whatever reason, in the middle of daylight savings change, I began to cut paste my old 2012 hyper-v avhdx / vhd files for my one server 2012 to another server as I was running  rapidly out of physical disk space on the host matching and I cut these from hyper-v folder INSTEAD OF selecting copy..

That's exactly what I did, it was the first time I did not force one or more snapshots and a bare metal backup, along with a file backup, and a good verify...

 I mean, I have royally, royally, majorly messed up on this one.. big time.. the worse mistake in 23 years.. The business's production file server, which was running server 2012 dc as a hyper-v vm.... Thankfully this has been the only huge, critical, screwedup, major mess up, but this one is taking the cake, making itself up for all the little snafu's mother luck has helped me to avoid for all these years..  This one makes up for all those years of luck... And I need help.. I have to get this vm up back into production, somehow before tomorrow..

MY QUESTION BEING.. (And I am BEGGING) for help please.. please..please..) Where do I start to fix this one?

 My screw up is so bad, I .. Wow. I don't even know what to say..

I am the cause for my own failure in this case, and wow.. oh boy oh boy oh boy.. Man.. I've done it this time... Wow...

ANY help would  be appreciated..

Where I am at now...  Obviously making a copy of everything related to all the VM, VHD and VHDX...   I cannot export anything or spin up anything without getting the mismatch error EXCEPT for the actual VHDX.. I can mount that as a virtual DIE drive and boot into the Server however, and obviously it is the initial creation of that specific vhd from may 2013, bypassing all the vhdx that hold my current data, files, etc..
I cannot mount any of the vhdx without getting the mismatch error..

Here is one of the exact errors from host 'prophet' while trying to start the file server vm, 'covenant':

(I get an error for anything I attempt to do such as export, or snapshot. This is the error upon attempting to start the VM)

Screenshot of actual misnatch error in hyperv manager when attempting to spin up VM on Server 2012 Hyper-V
'Covenant' failed to start..
Microsoft Emulated IDE controller (Instance 83F8638b-8DCA-4152-9EDA-2CA8B33039B4): Failed to power on with error 'The chain of virtual hard disks is corrupted. There is a mismatch in the identifiers of the parent virtual hard disk and differencing disk.'.
Failed to open attachment 'C:\users\public\documents\Hyper-V\Virtual Hard Disks\Covenant_199D3C68-B0DE-4F37-ABA7-19FC538DC3BE.avhdx'. Error: 'The chain of virtual hard disks is corrupted. There is a mismatch in the identifiers of the parent virtual hard disk and differencing disk.'.
Failed to open attachment 'C:\users\public\documents\Hyper-V\Virtual Hard Disks\Covenant_199D3C68-B0DE-4F37-ABA7-19FC538DC3BE.avhdx'. A problem was encountered opening a virtual disk on  the chain of differencing disks, 'C:\users\public\documents\Hyper-V\Virtual Hard Disks\Covenant.vhdx': 'The chain of virtual hard disks is corrupted. There is a mismatch in the identifiers of the parent virtual hard disk and differencing disk.'.
'Covenant' failed to start. (Virtual machine ID 4100AA76-26B9-4EB2-8DCA-16C2209-168C7)

Disk Settings for the VM on the host in the VM manager (screenshot)Current VM list in Host VM ManagerList of current files in hyper-v vhdx folder
Question by:WRAR-Admin
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LVL 123
ID: 39620274
Snapshots are evil things as you have no experienced, so my general recommendation is not to use them.

Seriosuly with this level of corruption, and not having the ability as Answers have to be via the forums, to be hands on.

Escalate this  to Microsoft Professional support ASAP, for them to Webex, and help you out of this issue, because the chain of snapshots has mismatches, that must be fixed, before you will be able to merge the disks successfully.

Accepted Solution

Smighty earned 2000 total points
ID: 39620284
Without reading everything I can tell you, I feel your pain. The longer I'm awake the worse the mistakes will get. If you grant me a personal advice: If you can't concentrate properly (and/or are tired), don't do anything. Even if that means, that a service is not available for the time beeing, its usually best to get rested and continue in a relaxed state... after all, the systems we manage are only as good, as the Admin that manages it ;)

Back to the topic:
All you need are all the pieces of the puzzle ;) - While differencing Disks are great to save storage, they can be a huge pain in the ass. I assume, you have lots of snapshots of the machines (which would explain all the .avhdx-Files for the same machine.

Hyper-V expects to find the Disks where it put it. As you are now experiencing, it is not particularily amused if you move the Disks yourself. (The Move-Wizard will help you to consolidate and move storage, the VM, or all together...)
You can look up where Hyper-V expects the parent Disk by inspecting the Hard Disk of the VM. - the AVHDX-Files then should be placed in the same folder than the VM-HDD.
That said, if all puzzle-Pieces are where Hyper-V expects them, the Machine will start.

I hope I could easy your pain a little. :)

Author Comment

ID: 39638987
Ok.. One week later... It is back up....
It was not as bad as I thought, but very, very, very time consuming..
I exported the VM, then imported the VM.. That got me up to June of this year...
I moved the snapshots over to a different machine which I created an iscsi storage block on...
And for each snapshot that was disconnected from the parent object, went to edit disk, and pointed ad the mapped path to the original snapshot.
All I can say is.. Lesson learned.. take time to verify your backups...

Expert Comment

ID: 39639577
I'm glad you could sort it out :)

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