We have recently started having problems with backing up one of our SAN drives and it appears this is because the deactivation of the snapshot is not working correctly. This leaves an old snapshot "mounted" (visible in disk management) and therefore seems to prevent newly created snapshots from being correctly activated. If we restart the server on which the snapshot is mounted the mounted drive is removed and the process works again for 1-2 days but the problem then re-occurrs.

We use admsnap (batch files run using scheduled tasks) in the following order:

1. On production host use admsnap to flush buffers (admsnap flush)

2. On production host start a session against the desired storage device (admsnap start)

3. On mount host activate the snapshot (admsnap activate)

4. On mount host perform backup / testing on snapshot device

5. On mount host deactivate the snapshot on backup device (admsnap deactivate)

6. On production host stop session (admsnap stop)

I have tried running the deactivate comand manually from command line but recieve the following error:

An error occurred while deactivating session "session-name" on device "\\.\PhysicalDrive6".
Error:  0x3E05003F (Session exists but not deactivated)

Error.  There were no devices deactivated for session session-name.

The production server and mount hosts are both running Windows Server 2008 R2.

Any ideas would be much appreciated.