Unlike Virtual PC 2007, why "Undo" disk on Windows 7's Virtual PC never get merged onto the main virtual hard drive (.vhd)?

Question

Using an "undo" disk on Virtual PC 2007, when the VPC is shut down, the program will ask, "Do you want to merge the change into the main virtual hard drive, or discard the change, or to save the change into a separate file".

But on Windows 7's Virtual PC, I tried using the same images as above, from the website

http://www.microsoft.com/downloads/details.aspx?FamilyId=21EABB90-958F-4B64-B5F1-73D0A413C8EF&displaylang=en

but this time, when I shut down the virtual PC, there was no question asked. The undo file (.vud) keeps on growing each time I boot up and shut down, and the original .vhd remains intact. Is there something that can be done to merge, or discard those changes? The .vud file is now about 1.2GB large.

Update: seems like no one knows an answer yet?

Answer 1

There is a separate option to do this in the VM's settings. See here for details: http://blogs.msdn.com/virtual_pc_guy/archive/2009/08/18/windows-virtual-pc-and-undo-disks.aspx

Answer 2

Here is some info from the VPC help file on Win 7:

If the virtual machine is running or hibernated, shut it down. For instructions, see Shut down a virtual machine manually.

Open the Virtual Machines folder.

Right-click the name of the virtual machine, and then click Settings.

In the left pane of Windows Virtual PC Settings, click Undo Disks.

In the right pane, click either Apply changes or Discard changes, and then click OK.