Where is the SQLS database backup virtual device string stored in the system tables?
This is old, but I had the same issue.  My SQL logs and backup tables were indicating that backups were happening, but even when I used the vssadmin command above, I could not locate the backup files.
I listed the writers, but none matched the long string in the SQL logs, so I tried some of the other "vssadmin list" commands:

---- Commands Supported ----

List Providers        - List registered volume shadow copy providers

List Shadows          - List existing volume shadow copies

List ShadowStorage    - List volume shadow copy storage associations

List Volumes          - List volumes eligible for shadow copies

List Writers          - List subscribed volume shadow copy writers

"List Providers" turned out to be the golden nugget.  Although nothing was returned for existing copies or storage associations, the Providers listed the info I needed - it named my SAN provider.  I looked in my storage tool and saw it was using Microsoft VSS, and the snapshot times correlated with what was in my SQL log.

Three things of note:


nowhere could I find anything to correlate to the  TYPE=VIRTUAL_DEVICE: number listed in my SQL Logs (even though there were plenty of guids all over)
"List Shadows" did not return anything, which was scary until I looked at my storage tool and saw the snapshots there.
My DBs are all currently in "SIMPLE" recovery model, so I never have to do anything but attach database mdf/ldf files from the snap.  This would be more complicated with databases that need to live in full recovery mode.


HTH future searchers - this has been bugging me forever.  Where were my backups?