Before moving to the next steps backup your master VHD:

1. Shut down virtual machine (do not “Turn off” it!).

2. Locate its .VHD and copy it to some safe location, say to “M:\VPS\Master\Backups” folder. You can see the exact location of VHD file by opening VM properties dialog:

Important note: Do not make system snapshots as it leads to creating differential virtual hard drives (you may check this article for more info about Hyper-V Snapshotting: http://blogs.msdn.com/virtual_pc_guy/archive/2008/03/11/virtual-machine-snapshotting-under-hyper-v.aspx) and as a result master template will be broken into several parts.

After making VHD backup start VM again.