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Cloning Windows Server Backup Targets

posted Oct 2, 2013, 1:51 PM by Jeremy Walker
I recently ran into a case where a target of Windows Server Backup began failing. Luckily the external hard drive was under warranty. However, the customer wanted to retain the 200+ backups that WSB made to it. So I cloned it thinking that WSB would identify the drive by the Volume Label. I was wrong - WSB did not recognize it as the original external hard drive. So I did some digging on the web. I found these three pages that, when put together, helped me figure out what to do:





and


Yeah, that was a lot of digging... So I learned that Macrium Reflect gave my new external hard drive a new Disk Signature to avoid a collision. That also meant Windows gave the new drive a new GUID path. By deductive reasoning I could safely assume that Windows Server Backup identifies target disks by their GUID path. All I had to do was set the new drive's Disk Signature in the registry key for the old drive's GUID path. Here's the outline of what I did:
  1. Browse to HKEY_LOCAL_MACHINE\System\MountedDevices using Regedit.
  2. MAKE A BACKUP OF THE MountedDevices KEY BY EXPORTING IT!
  3. Run mountvol from a command line to help determine the GUID path of the two volumes.
  4. Dismount and unplug both drives.
  5. Copy the first four bytes of the value related to the GUID path for the new drive in the MountedDevices key then paste them over the first four bytes of the value related to the GUID path for the old drive.
  6. Remove the name/value pair that Windows created for the new drive.
  7. Re-connect the new drive only.
  8. Drink a beer.
  9. Celebrate.
After that, Windows Server Backup recognized the drive and I could backup to it successfully.
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