For collocated pools, if there are available scratch tapes, a single node is
assigned to a tape.  Only when you no longer have available scratch tapes
does TSM start "stacking" nodes on a tape.  If you want to minimize tapes in
your copypool, I would suggest either not collocating or setting a low
enough maxscratch number to force TSM to start stacking multiple nodes on a
tape.  For more informaiton, the Admin Guide has a section describing tape
selection criteria and precedence.

Alex