Last week I had a client with a crashed hard drive on their Hyper-V server. Coming from a physical server world, they had performed file-level backups of all the virtual machines and virtual machine files on the system. Expecting to just recover the files to the new RAID array and use the “Import virtual machine” feature of Hyper-V Manager, I was shocked to learn that unless you perform a specific “Export virtual machine” step, you cannot import a virtual machine file.
When you only have a simple VM that consists of a single VHD file and no snapshots, things are quite easy to restore: create a new virtual machine with the same physical configuration and attach the existing VHD. Open and shut, done in 5 minutes or less. However, if the machine has had snapshots, even if you have since removed the snapshots, chances are the individual snapshot files are still floating on the hard drive and are required for full recovery.
What I ended up doing was following the very helpful instructions located here for Option 2 and recovered both machines to the server in about 45 minutes. Very easy, very straightforward, but also very unsupported. Lacking a Hyper-V-aware backup, though, this was the best option for me.
Going forward, we have implemented Hyper-V-aware backups using the Microsoft Data Protection Manager 2007 with SP1 software and iSCSI mounted storage. Alternatively, BackupExec 12.5 has an option available that makes BE aware of the Hyper-V machines and can independently backup their configurations.