Posted by: kurtsh | October 26, 2006

INFO: Windows Vista Backup & Restore uses Virtual PC .VHD files

In case you hadn’t noticed or heard, Windows Vista’s backup utility is a program called "Windows Backup".  It’s special because unlike Windows XP’s backup utility, when you do a FULL backup of your system, it creates a .VHD file which contains the contents of the drive.  For the uninitiated, this is the same "virtual hard drive" file format used by Virtual PC virtual machine hard disks. 

You would be correct in saying, "Whoa.  That’s cool."  And yes, it does this all ONLINE and LIVE.  You don’t need to shutdown or halt any usage of the file system… it does it all like a "snapshot", to use server backup terminology.

Good news & Bad news
Now there’s good news & there’s bad news according to my peer, Michael Greene:

  • Here’s the buzzkill:   This isn’t an actual P2V tool.  In other words, it’s not creating a virtualized version of your workstation which can be "booted" in Virtual PC.  There are efforts underway by 3rd parties to actually get these .VHDs to boot up but as it stands, no such opportunity exists.  I suspect that it would have been trivial to make these .VHD bootable – in fact, they probably initially had the .VHD bootable however the potential for conflict between two identical workstation on the same network would be too great, not to mention the licensing implications of not just the OS but also the software duplicated in the .VHD.
  • Here’s the upper:  You can mount the .VHD file just fine using the VHDMOUNT tool.  Mounting is UNIX terminology for accessing a resource as a virtual directory or as a virtual drive on your workstation.  In other words, it’s possible to view the contents of the .VHD file as if it were just another directory on your computer.

This would obviously be useful for recovering a few "backup files" that you might need on the spur of the moment from a previous snapshot. 

Double Click to Mount
What makes this even cooler is that it’s possible to "double click" on a .VHD to instantly mount it, without much effort at all.  Virtual PC Guy’s Blog (Ben Armstrong) posted instructions on how to do this here:


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