The ninth sessions goes to the ninth disk volume allocated in my
environment.  I have not had a need to test this situation.

In my environment, I would have 36 volumes if I had 8 * 9 gigs drives.

An SSA disk drive can write 30 meg per second (do a move data and see)
Multiple clients can write to one disk at the same time.  And if you have
multiple volumes, the question does not come into play.   Faster than a 3590
tape drive fiber attached can receive the data also.  (12-13 Meg per second)
You can just watch the Brocade switch and see the different speeds exactly,
though you can't forget compression in most enviroments.  (I compress on the
client, so I can just about though)

Jeff Bach
Home Office Open Systems Engineering
Wal-Mart Stores, Inc.

WAL-MART CONFIDENTIAL


        -----Original Message-----
        From:   Lindsay Morris [SMTP:lmorris AT SERVERGRAPH DOT COM]
        Sent:   Thursday, August 30, 2001 2:57 PM
        To:     ADSM-L AT VM.MARIST DOT EDU
        Subject:        Re: TSM DB/Disk Pool - Disk tuning question

        Jeff, clever! run iostat, then watch sessions start and land on
different
        physical disks, on by one.
        Like the idea.

        But what happens when you run out of volumes? Say you have 8 disk
volumes,
        and 9 sessions.
        Does the ninth session just hang, until one of the first 8 finishes?
        Or does the ninth session grab some busy volume, sharing it with
another
        session?

        > -----Original Message-----
        > From: ADSM: Dist Stor Manager [mailto:ADSM-L AT VM.MARIST DOT EDU]On
Behalf Of
        > Jeff Bach
        > Sent: Thursday, August 30, 2001 3:49 PM
        > To: ADSM-L AT VM.MARIST DOT EDU
        > Subject: Re: TSM DB/Disk Pool - Disk tuning question
        >
        >
        > 1.  A single backups runs to a single volume as perceived by ADSM.
The
        > first session runs to the first volume allocated to the storage
pool.  The
        > second session runs to the second logical volume allocated to the
storage
        > pool.  The third sessions to the third volume.
        >
        > With THIS understanding, you can effectively stripe by allocating
volume 1
        > from each drive first, then allocate the second volume from each
        > drive.  You
        > can see the threads using "show threads".  Run one session, watch
iostat,
        > then start a second and third.  You should be able to see what my
        > understanding it easy enough (or at least tell me I am wrong)


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