I have a SBS 2011 server which attaches to a VHD. This has been operating without a problem to date. Yesterday I had to move some old mailboxes off the Exchange Mailbox database so I created a new database on the VHD and ran a move request on the Users mailboxes.
It maybe coincidence but once the mailboxes moved the VHD was dismounted. I ran the mount script and it mounted and then again within a minute or so it dismounted. I tried via the GUI but the same problem occured.
I'm not how Exchange could force a dismount of the VHD but it seems something is.
The VHD is located on a NAS drive.