> Given a file that has been backed up by a node, how do I find out which
> tape the current copy of the file is on without doing a restore?

You can do this with the unsupported 'show' commands.

show versions jupiter /home /jsmith/ .profile

will return information on all backed up versions of /home/jsmith/.profile
from node jupiter. This will include a line like:

ObjId 0.123456

The command

show bfo 0 123456

will either return information that includes volume names for the primary
storage pool and any copy storage pools or inform you that the object is
part of a specific super-bitfile. In the latter case, running another
'show bfo' for the super-bitfile will return information that includes
volume names.

The elapsed time for the 'show versions' command seems to depend on the
number of files in the file system. I have seen this command take minutes
for the file system containing our electronic mail store, which has
several million files.