First as background - most of our MVS DASD is STK Iceberg/RAMAC Virtual
Array.   As a standard, most of our devices (including the ADSM DASD) is
formatted as 3380K.  So to answer your questions - for our backup pools, we
use 3380K Images, and format the whole volume - as a matter of fact we avoid
a lot of the performance stuff - we allocate a single cylinder VTOC at the
beginning ot the disk - not in the middle - and then allocate the biggest
VSAM space we can get.  This works out to 1.5GB in round numbers.

We have two primary Disk pools - one for servers, and one for Desktop
machines (regular PCs and Laptops).  We separated because we treat the tape
pools that they migrate too differently - servers get a collocated tape pool,
while desktops do not.  Curently there are 11 volumes in the server pool
(16GB apporx.), and 2 in the Desktop pool (for 3GB).  Archive is not yet
heavily used, and so we keep these pools small - there are two pools here
also, but both are small - 500MB each - both on th esame volume.  no big
contention here either.

I am not sure what you mean with Virtual volumes - Iceberg has things all
spread around anyway, due to the RAID 6 configuration.  The logical volume of
course could be mapped anywhere; we don't know and I haven't had any need to
worry about it.  Because of all the cache the Iceberg has in it, I don't have
problems with hits, either.  In fact, the only problem we have is that the
data is already compressed before it hits the Iceberg, and so is not
compressed much more.  This throws off the compression ratio for the box, but
not so much that we haven't hit the target for the device.

Hope this helps.  If you have any other questions, please respond to me
directly.

Jerry Lawson
jlawson AT thehartford DOT com


______________________________ Forward Header __________________________________
Subject: Diskpool configurations on MVS.
Author:  INTERNET.OWNERAD at SNADGATE
Date:    5/21/97 11:10 AM


      I've asked this question once before and received no response so I'm
     re-sending and begging this time as we are starting to see some
     performance problems.

      If you MVS ADSMers would be so kind as to enlighten me as to the
     following:

     1. How many DISKPOOLS do you have configured?

     2. How many virtual volumes do you have configured for each physical
        volume? What size?

     3. How are your virtual volumes defined to the various DISKPOOLS.

     4. Is anyone experiencing any performance or IO problems related to
        ADSM hits on the DASD? If so how are you dealing with them?

     We're desperately searching for some information so any light you can
     shed would be greatly appreciated. Thanks in advance.

     Damon Taylor

     Amoco Corp.