We have a 3494 with 8 3590's. Our ADSM Server is running on an SP2 wide node.
To respond to your questions:

1) We backup the Library Manager Workstation to ADSM. The LM worstation is
networked.

2) I have 4 3590's on ADSM. There are two 2412 SCSI cards in my SP2 wide node
for tape, so I daisy chain 2 drives on each SCSI card. While I would prefer to
have dedicated drives to SCSI cards this is not a reality in a limited slot
environment. I have not noticed that there is performance degredation due to
the daisy-chaining. There are so many other performance issues around network,
disk and ADSM itself that tape is the least of my concerns.

3) There are two SCSI ports on each 3590 drive. We utilize all of these to
improve the usage of our tape drives. I would not call the sharing dynamic,
however, it works most of the time. The drive itself will not let two
interfaces write to or utilize the same drive at the same time so integrity of
the data on tape is preserved. Our non-ADSM backup scripts all release the
drive when the drive usage is completed.

ADSM is not quite so friendly when it comes to tape sharing. We have
requirements to ADSM in IBM's requirements database to fix this and anyone who
wants to add a "me too" to these requirements would be welcome.

With ADSM we use the adminstrative schedule to attempt to delete the drive we
need to free for other usage. We start several hours in advance of when we need
the drive since Delete Drive will not work if the drive is in use. We issue the
command once an hour and hope that we can catch the drive free. We use another
adminstrative event to add the drive back to ADSM when the schedule from the
other non-ADSM system indicates that the drive will be free.

Hope this helps

Paul Hilton
philton2 AT isma DOT com


To: ADSM-L @ VM.MARIST.EDU (Multiple recipients of list ADSM-L) @ Internet
cc:  (bcc: Paul Hilton)
From: tlaporte @ DREAMWORKS.COM (Tom La Porte) @ Internet
Date: 26/08/96 04:24:07 PM
Subject: 3494 Tape Library and ADSM

I had some questions for anyone using a 3494 Automated Tape
Library with ADSM.

1) Do you backup the Library Manager Workstation via ADSM? If
   so, is your ATL networked or is it communicating to a host
   via a serial cable?

2) I have six 3590 drives in my ATL, three of which are connected
   to the host directly (i.e. each to its own SCSI card). What
   type of performance loss will I experience if I have to daisy-
   chain the disks?

  (For reference, the other three drives are connected to
   to other nodes of an SP2, and are not configured to be
   used by ADSM--is there a way for two different nodes to
   dynamically share all six drives?).

Thanks for any information. -- Tom

What if the Hokey-Pokey              Tom La Porte
is what it's all about?              <tlaporte AT dreamworks DOT com>