Snapshot failure when VMs and VHDs are on different disks

[telefunken-u47]

Hi,

I'm new to VirtualBox, but I have a few years of light experience with VirtualPC and VMware.

This past weekend, I installed VirtualBox (on a Win7/x64 host) and set up two VMs (both Win7, one x64 and one x86). I created fixed-size (96GB) .VHD-format disks for each guest. Because my host has a relatively small (240GB) SSD for its C: drive, I put the .VHDs on another (1GB spinning) disk mounted as the T: drive.

Following guest OS installation, before making any further changes, I pulled Windows Updates for both guests until they were current. I then created "clean" snapshots for each, and shut down the guests and the VirtualBox manager application.

Later, when I started VirtualBox, I got warnings from the Media Manager that the (snapshot) disks for both VMs were inaccessible. Trying to revert to or delete the snapshots produced error messages complaining of all-zero parent UUIDs, similar to this one from an unrelated thread:

Code: Select all

Parent UUID {00000000-0000-0000-0000-000000000000} of the medium 
'C:\Users\Seajay\Virtualbox VMs\Subversion Server\Snapshots\{c3e264e8-6102-471d-befa-190de559732d}.vhd'
 does not match UUID {f7db-4bde-a65c-437e-8687-0b7aaeafd328}
 of its parent medium stored in the media registry ('C:\Users\Seajay/.VirtualBox\VirtualBox.xml').

I deleted and re-created the VMs several times (attaching them to the existing .VHD files), and the problem persisted. Finally, out of suspicion, I changed the "Default Machine Folder" (File->Preferences->General) to point to my T: drive, re-created the VMs again, moving the .VHD files inside the associated VM folder, and now everything works correctly.

So, it seems as if VirtualBox gets confused when (some part of) the Virtual Machine resides on one drive, while the base .VHD resides on another.