In ADSM, tapes become full but the data on the tapes expires.  You
will see that a tape is full but only 35% used.  This is because of data
expiration.  With two tape drives, when this situation occurs ADSM can
automatically move the good data to a different tape drive within the
library thereby making the tape that was 35% utilized available again.

  With one tape drive, you have to manually move the good data from the
35% used tape to a different area.  This movement can be performed using
the move data command which you can type in or can be put into a script.

  If all the tapes in your library fill up then your library is full and
no more data can be put in it.  It doesn't matter if the tapes are 100%
utilized, 1% utilized or anything in between.  Once a tape is full its
full and the only way to be able to use the tape again is to reclaim the
space containing the expired data on the tape.

  ADSM is much better with multiple tapes drives in libraries.  Single
tape drives create more work and headaches.


> We are new to ADSM. We have a 3570-Bll (one drive) tape subsystem
(Magstar MP).
> Now we have been told that to fully utilize ADSM we need to go to
3570-B12 (two
> drive) tape subsystem..
> Been trying to find info on this and have had no luck.
>