Recently I was asked how to do a granular restore of a Hyper-V VM from a backup done by Windows Server Backup (the block-level image backup).

The Windows Server Backup Recovery Wizard allows you to restore Hyper-V, but it’s an all-or-nothing affair. Restore all your VMs or none at all.

So how do you recover one specific VM – especially to different machine (host)? Unfortunately it’s totally undocumented by Microsoft, and it’s not just a matter of restoring your VM’s directory and asking Hyper-V to open it up – because Hyper-V can only “import” a VM that had been specifically “exported”; it can’t import a VM from a backup.

Restoring on the same machine

Scenario: the virtual machine’s setup and configuration are fine, but you need to restore the virtual hard drives.

1. Stop the Virtual Machine from the Hyper-V Manager
2. Optionally copy your old VHD file(s) to somewhere else, just in case…
3. Restore the VHD file(s) for that machine to the same location.
   • Launch the Windows Server Backup admin console
   • Click on “Recover” in the right hand pane
   • Choose the following options: “This Server” -> the appropriate point in time -> Files and folders [note: not Applications] -> locate your VHD file(s) -> recover to Original Location
4. Start your Virtual Machine from the Hyper-V Manager
5. If the VM was running at the time of your backup, the boot manager will point out that the machine was not shut down cleanly. That’s fine – just boot normally.

Restoring to a different host machine (or same host machine with corrupt config)

Scenario: virtual machine needs to be restored to a different host. However, it’s not possible to import a virtual machine onto the new host from a backup. Instead, follow this procedure.

1. Restore the VHD file(s) for your virtual machine to a new location.
• Launch the Windows Server Backup admin console
• Click on “Recover” in the right hand pane
• Choose the following options: “Another Server” -> the appropriate point in time -> Files and folders [note: not Applications] -> locate your VHD file(s) -> recover to Another Location, and choose a directory to restore to
2. Create a new Virtual Machine from within Hyper-V Manager.
   • Set the RAM to match the RAM of the old machine
   • Set the network card to match the network card of the old machine
   • For your virtual hard disk, select “Use an existing virtual hard disk” and point it to your first restored VHD.
   • Complete the wizard.
   • If you had more than one HDD, stop the machine, add in the extra HDDs (File -> Settings
3. If the VM was running at the time of your backup, the boot manager will point out that the machine was not shut down cleanly. That’s fine – just boot normally.
4. In our tests, we did not have to reactivate the virtual machine when running on a host with dissimilar hardware. However, that’s no guarantee that you won’t need to reactivate it on your environments.

This entry was posted on Friday, April 3rd, 2009 at 3:38 am and is filed under Support. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.