One good idea to phase in backing up your storage pools is to just
backup your disk storage pool (before migration) for awhile.  This way
you will back it up before it gets migrated to tape.  If you do this for
a few weeks, overtime files on the tapes will expire.  When you later do
backup your tape storage pool, there will be much fewer files that
needed to be backed up from tape since the backup stgpool is an
incremental backup.

Even after you do finally backup your entire tape storage pool, you
probably will want to continue to try to backup the data while it is
still on disk to avoid tape mounts.

Yes, periodic reclamation of offsite volumes is important to reduce the
number of volumes offsite that contain active data.  Make sure you use
and understand the REUSEDELAY interval.

There is an APAR relating to offsite reclamation: PN85243.  I don't
believe it is closed yet, but we do know what the fix is.  The problem
is that sometimes only a subset of the eligible offsite volumes are
reclaimed during a reclamation cycle.

Dave Crockett - ADSM development