Hi Daniel,

I have a Magstar MP 3575 L12 (120 tapes, 4 drives) and a 3570 B02 (2
drives). The 3575 L12 is used for tapes of the primary storage pools only
and I never check out a tape from there. The 3570 B02 is used for copy
storage pool only.

In general you only have to check out tapes from a library due to security
reasons (move tapes to a vault), no free storage slots available,
unrecoverable media errors, etc. But note that it is strongly recommended
to backup your primary storage pools and adsm database and archive the
tapes offsite in a vault.

Every morning the operating people check in all the tapes from the copy
storage pool that are 'filling' tapes, 'empty' tapes, 'old' adsm database
backup tapes or have a 'pct. reclaimable space' value greater than 60 %.
The tapes are taken from a vault offsite this building and checked into the
3570 B02. Once, all the neccessary tapes from the copy storage pool are
checked in and marked as 'onsite' (means access mode ReadWrite) the
reclamation threshold of the copy storage pool will be changed from 100 to
60 which starts space reclamation for the equivalent copy storage pool
tapes. If all tapes are reclaimed the reclamation threshold will be changed
back to 100 so space reclamation doesn't occur automatically. Now all the
primary storage pools will be backed up to the copy storage pool. After the
copy has finished I do an adsm database backup. At the end, all 'full' and
'filling' tapes of the copy storage pool will be checked and marked as
'offsite'. In addition the adsm database backup will be checked out to and
all tapes go back to the vault. (Note that adsm doesn' t need a copy
storage pool volume 'onsite' to reclaim it. It can be done by processing
the equivalent tapes from the primary storage pools).
In your situation I would prevent space reclamation to occur automatically
and start it by updating the reclamation threshold if all tapes needing
reclamation are checked in.

Regarding to your second question (after 60 minutes a tape will be marked
as 'unavailable' if it could not be loaded) it depends on how many drives
your 3570 library has and if the tapes are in the library. If your have 2
drives and the tapes are in, I would set the mount retention of the device
class to a value less than 60 minutes (e.g. 1). This will dismount 'idle'
tapes from the drive(s) after the interval you have defined.

Hope this will help a bit.
regards
Rainer