From: Mike Knight, IBM GS Central, (314)234-5096, KNIGHTM at ISSCVM
Inet:                                             KNIGHTM AT VNET.IBM DOT COM
Subject: 3494/3590 question

We only have one system accessing our 3494/3590 library, but just ordered
an upgrade to allow attaching a second ADSM/6000 server (on a separate
RS/6000) to the same library.  My understanding is that you can cable the
drives to both servers and then do static sharing of drives, where each
drive is only defined to one ADSM server at a time.  Systems like JES3
and BRMS/400 may provide the proper coordination between systems, but
this is system dependent.  We plan to define half the drives to each
ADSM/6000 server and manually delete some on one and define them on the
other if there is a long term load imbalance or hardware problems.

You also need different private and scratch categories for the ADSM servers.
The "ITSC Guide to Sharing and Partitioning IBM Tape Library Dataserver"
(SG24-4409) covers most platforms including ADSM/6000.  It can't hurt.

After a 3590 lost its power supply, ADSM kept trying to use it and
generated 10 errors per second for the whole weekend.  I am concerned
that the same would happen if one system had a drive reserved and the
other wanted to mount a tape in that drive.

         Mike (Not ADSM support, personal opinion) Knight

On Mon, 10 Mar 1997 09:37:27 -0800, Thomas A. La Porte asked:

>I'm wondering if, b/c the 3590s are twin-tailed, I can hook all
>six 3590s to each of the two ADSM servers without causing any
>conflicts. Since tape requests and such go through the library
>manager control point, would there be any contention for the
>drives that would cause problems? I realize there will be
>contention, but I'm thinking that the 3494 will arbitrate things,
>and at any given point a single ADSM server could have access to
>all six drives, assuming none are being used by the other server.