I am still on ADSM 3.1 with OS/390.  I have found variants of this query
impossible to
run during normal hours, when other users (online business) seem to think
they are
more important than mere housekeeping functions.

Running out of hours, my query (select node_name from volumeusage where
stgpool_
name='xxx') can run for a couple of hours using virtually all of a 60 MIPS
engine.

The volumeusage table has more rows than you might think.  There seems to
be a row
for each "collocation cluster" on a cartridge, and on 20GB volumes with
data from the
Lotus Notes agent, I sometimes see many hundreds of clusters on one volume.
Even
so, with only a hundred or so volumes, I find the CPU consumption rather
over the odds.

Maybe it gets worse with 3.7, but it would be worth having a look at the
dispatching priority
of your TSM server, and what other work might have been running at the same
time.

Good luck,
Geoff Fitzhardinge
Australian Gas Light Company