Richard,

thanks for your reply. I've read the two definitions carefully but still
don't understand
what's going on (but this happens very often to me :-))

I wonder why the Physical occupany differes between our tape pool and the
copy pool.
In the morning we start migration from the disk to the tape pool and when
migration has
finished we immediately start the BACKUP STGPOOL TAPE COPY.
That's why I wonder how the physical occupancy can be different on this
tapes - because
the content even of the aggregates should be the same.
It could be no question of ADSM doing some optimization because sometimes
more space
is required on the TAPE storage pool, sometimes on the COPY storage pool.

It really doesn't matter but ADSM often does some umexpected things
(unexpected to me)
and I always like to know why ADSM behaves the way it does.

Kind regards
Thomas Rupp