Взято тут:
http://social.technet.microsoft.com/wiki….-v.aspx
Manually Merge .avhd to .vhd in Hyper-VHyper-V brings to life several additional disaster recovery scenarios that can be leveraged to our advantage when the need arises. One of the features that really comes into play are VM snapshots. A Snapshot is basically a spot in time where the current running configuration of the Virtual Machines is saved to a Snapshot Differencing Disk file (AVHD), from which you can return to from the future. This tip will show you how to manually merge hyper-v snapshots into a single VM for point in time restores.