>What is the best way to find out what volume (tape) a certain file is on?
>Is there a command?

Chris - The painful way, depending upon your file population, is to do
        the old Select on the Contents table, to get the volume_name
for a given file_name.
    The dirty trick way is to mark your backup storage pool Unavailable
for a moment, attempt a restoral, unmark, and look in the Server Activity
Log for what volume it could not get.
         Richard Sims, BU