One doesn't retain tapes but rather files.  When sufficient files on a tape
have expired, the tape becomes a reclamation candidate.  Once reclamation
runs for a tape, then that tape can be reused.

In the case of off-site tapes, the reclamation threshold is typically set to
100%.  That is, don't reclaim them until they are empty.  What most of us do
is to periodically drop the reclamation threshold on the off-site pool to
start reclamation.  This is done by writing new tapes using the data on the
primary, or onsite, tape pool.  Takes time, but it will free tapes in the
offsite pool.  These will then be shown as offsite 0% utilized, or vault
retrieve if you have DRM.  These tapes can then be recalled.

To determine when files expire, you will set the values of retain extra,
retain only, verdeleted and verexists in the backup copy governing those
files.  Once you reset these values, you must activate the policy set.  If
you lower these values, the next time file expiration processing runs, you
may recover space on your tapes.  That is, tapes will become more
reclaimable.


Kelly J. Lipp
Storage Solutions Specialists, Inc.
PO Box 51313
Colorado Springs CO 80919
(719)531-5926
Fax: (719)260-5991
www.storsol.com
lipp AT storsol DOT com