Richard,
Depends on how you configure ADSM - (hey! that's and easy out to your
question)

We have v1 on MVS (it was installed 2+ years ago as a temporary measure),
but I've gotten by with 2 drives.

All backups here are configured to go to primary disk pool.  Once full, the
secondary storage is tape.  This will utilize a drive for less time doing
the migration than a direct to tape backup.  All our clients doing backups
are set to do client compression.  This allows more data to be stuffed on
the disk pools before migration is required.

I have the tape retention set at 3 minutes.  Once the migration or restore
process is finished, ADSM will deallocate the drive fairly quickly.

Since most tape access is migration, a restore really doesn't affect me,
since the migration will resume at the point where it stopped.  At this
level of ADSM, I don't even know if a restore will supersede other
processes.

We don't have a library, so I do not do colocation (I did once, and the
operators complained bitterly).

If I am doing special work, I can issue a MVS modify command to ADSM to
utilize more (or less) number of drives.

Randall Eggert
MAPCO, Inc.
Tulsa, OK
(Just down the street from the old Texaco building)





"Wendrock, Richard O" <wendrro AT TEXACO DOT COM> on 02/19/98 07:17:12 AM

Please respond to "ADSM: Dist Stor Manager" <ADSM-L AT VM.MARIST DOT EDU>

To:   ADSM-L AT VM.MARIST DOT EDU
cc:    (bcc: Randall Eggert/TUL/MAPCO)
Subject:  Planning for tape requirements for MVS




I am trying to determine how many tape drive we will need for ADSM on MVS.
How does ADSM manage tape drives on MVS?
Is there a priority amongst ADSM subtask?  Does a request for recover carry
a higher priority over backup?
When does ADSM release a tape drive? (at end of tape or end of task)

Regards,