>The main culprits are the *.dsm files for log, db and the disk pools.

ADSM has historically created these in /var (rather than /usr) - regardless of 
whether
one already had "real" ones in other areas, as it should note in dsmserv.dsk.
I keep it from wasting space by doing a 'touch' in /var of each file that it 
will
create, thus making an empty copy, which the install sees and leaves alone.
   Richard Sims, BU