ADSM-L

Re: ADSM database volumes/disks/performance - question

1997-04-14 12:41:14
Subject: Re: ADSM database volumes/disks/performance - question
From: "Pittson, Timothy ,HiServ/US" <tpittson AT HIMAIL.HCC DOT COM>
Date: Mon, 14 Apr 1997 12:41:14 -0400
Tom,
        When I migrated ADSM from MVS to AIX, I went back and forth as to
whether to put the ADSM database on SSA disks or a disk array.  After
posting a question on this list server and receiving some good feedback,
we ultimately decided to put it on a 7137-514 disk array, with the
recovery log and storage pools going on SSA disks.  One user posted some
ADSM benchmark numbers for a similar environment to yours (SSA vs disk
arra, RS/6000 model Rxx) last summer which was very helpful in our
decision - you might want to search the archives for that information.
We've been very happy with the performance, even without using raw disk.
 Also noticed you've got 128 MB of memory - might want to consider
bumping that up as the ADSM database will take advantage of it (just
like any other database - the more memory, the better).  Our database is
about 12 GB and I've got the db bufferpoolsize set to 64 MB  (note - you
might not be able to go any higher than this due to a bug in the ADSM
2.1.5.12 code - supposed to  be fixed soon).  I  try to keep the db
cache hit % above 99% - that might be unrealistic in some cases but we
have the memory to spare and I've noticed it makes a big difference.

Hope this helps...

Tim Pittson
tpittson AT himail.hcc DOT com

>----------
>From:  Tom Tannes[SMTP:tom.tannas AT USIT.UIO DOT NO]
>Sent:  Monday, April 14, 1997 11:00 AM
>To:    ADSM-L AT VM.MARIST DOT EDU
>Subject:       ADSM database volumes/disks/performance - question
>
>Hello adsm'ers!
>
>Our ADSM-server is running out of disk-space, so we need to add more disks.
>
>I would like to hear from other adsm-users what are their experience whith
>different disks/disk-subsystems to hold the db- and log-volumes
>
>The server is a RS6000/R30 whith two 604 CPU's and 128MB memory installed.
>The OS is AIX 4.1.4, and the adsm-server is 2.1.5.12
>
>Our current configuration consists of 12 4.5GB SSA-disks which holds
>the db-volumes, log-volumes and the disk-storage-pool-volumes.
>
>The database is currently using about 30GB of this space, an is still growing
>rapidly, which causes the need for more space.
>
>I also have problems whith high disk I/O-wait, often 80% and more on the db-
>volumes, even if I manage to keep the cache hit % above 95.
>The cache is 30MB which seems to be the limit for us before things start
>paging
>heavily.
>
>All our adsm-volumes are raw disk volumes, and only the recovery log is
>mirrored.
>
>Because of the 2GB volume-limit in adsm we have 3 volumes sharing each disk
>to
>be able to use all the disk-space. I've had the feeling that this was wrong
>from the beginning, but the 4.5GB-disks was what IBM recommended for us.
>
>
>What whill be the best thing for us to do?
>
> - Add more 4.5GB SSA-disks?
>
> - Add even more 2GB SSA-disks?
>
> - Move the whole database to a RAID subsystem?
>
>
>Any hints/experiences/suggestions would be appreciated.....
>
>
>
>
>                                            Tom Tannes
>
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