Take a snapshot and attached disks are detached

[Mark Cranness]

In some circumstances (VMs with shared attachements), takeing a snapshot causes attached drives to be un-attached / removed.

Repro:

• Two new machines (A, B) with no attachments, 5 virtual disks: A1, A3, B1, B3, SHARED.

• Attach to A the following disks (in this order): A1, shared, A3 and add a CD/DVD controller and drive and a floppy controller and drive.

• Attach to B the following disks, B1, shared, B3 and add a CD/DVD controller and drive and floppy controller and drive.

• Take a snapshot on A. Not that now only A1 is attached, and the other disks AND the CD/DVD drive and floppy drive have been removed.

• Attempt to-reattach A3 to VM A. Note that A3 is shown with the blue star icon, indicating that a differencing disk is attached somewhere (so VB thinks).

• Virtual Media Manager > Observe that A3 does NOT have a differencing disk.

• Restore Snapshot on A and Delete Snapshot on A

• (STRANGE!) Repeat add drives to A and snapshot and this time the snapshot does not remove the attachements!

• Delete Snapshot, and observe: "Failed to delete the Snapshot 1 of the virtual machine A. Medium 'C:\...Shared.VDI' is locked for writing by another task."

• Close VirtualBox, wait for VBoxSVC.exe to stop, Delete snapshot 1 works. Re-add snapshot, followed by Delete snapshot gives error above again.