I am running W2K8 R2 as a Hyper-V host. I have a W2K3 R2 running as a VM on it. I deleted 3 snapshots from Hyper-V Manager. This started the Merge process (I could see it in the status column), it was brief. The VM was OFF during this process. I checked the physical files folder and the avhd files still exist with vhd file. The merge process did not delete or merge the avhd files. I started the VM and then shutdown, same thing. I see merge process in the status column briefly and then it dissapears. No errors. Checked the files folder the avhd files still there. I researched and found manually merging it using the disk edit. Tried it but it runs half way and give an error about not being able to merge the avhd file to its parent vhd.
When I check the virtual hard drive path it is pointing to the avhd file instead of vhd file. Any suggestions on how to merge avhd files into one vhd file? Thanks in advance!


Do you have enough disk space for the merge to complete? Do you see anything in the event logs? I believe you'd be interested in the Hyper-V-Image-Management-Service log specifically, but take a look around. Hyper-V Logs

Update: How big are the AVHD's and the VHD that you're merging? I'm not sure what would be accessing this file, but you could try turning on file audit access for the VHD and the AVHD to see if something grabs it while it's merging. Maybe antivirus? Is all of this being done on local disk or are you making use of NAS or iSCSI?

Update 2: You definitively do not have enough space to perform the merge. You would need at least 286 GB to perform the operation. You have a couple of options: You can attach a USB drive and perform the merge using that extra space. Otherwise, you can perhaps do one snapshot deletion + merge at a time (if that would get you under the 133 GB).

  • +1 Hyper-V will not auto-merge unless it has as much disk space free as the original vhd and avhd files currently take up. Essentially it makes a whole new vhd file from the existing files. Also might be worth running chkdsk in the VM. – Chris S Aug 31 '11 at 14:15
  • I have 130 GB free disk space. – Shazam Aug 31 '11 at 14:30
  • I look in the Event Viewer for Hyper-V and do see Errors. The Errors are:"Background disk merge failed to complete. The device is not ready." – Shazam Aug 31 '11 at 14:32
  • Another Error: "The system failed the merge "C:\......". Error Code: 2424869, Another Error: "The process cannot access the file b/c it is being used by another process." I had the VM turned off the whole time?! – Shazam Aug 31 '11 at 14:33
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    Export the VM. Physically move it to the attached USB drive. Re-import it. Start it and then shut it down. This will initiate the merge process. This will not be a quick process. More info here: technet.microsoft.com/en-us/library/dd560637(WS.10).aspx – pk. Aug 31 '11 at 21:09

Try removing the virtual DVD drives from the VMs. It sounds like it is not able to access them both. If both work after the DVD drives have been removed? Then readd them and see if they work after that.

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