My suspicion is that the legal request is a lawyer's pro forma procedure 
written in the 1980s for collecting evidentiary information in a data 
processing environment: "Obtain a list of the tapes upon which the data 
resides".  It's likely that they don't actually care what tapes are involved: 
their goal is to generate a list which contributes to an impressive compendium 
of factoids which fill lawyerly paper.

Given the size of TSM tables, my inclination would be to narrow down to a set 
of tapes, which you know by virtue of common storage pool and perhaps 
collocation by node.  Then perform 'query content' on each volume, output to a 
file per volume, which you can subsequently grep for containing the files of 
interest.  Query Content is tailored and efficient, greatly reducing time and 
impact.

    Richard Sims    not a lawyer