You say you put it on SAN. What kind? I am guessing a Shark or FastT
device since it is an IBM SAN. If you only got 10% with Oracle and the
issues with TSM on the database I think you have your file systems on the
AIX machine setup incorrectly or another problem. It could be the tape
drive is the problem on the backup, especially if you are using the same HBA
for both a SAN Data Gateway (IBM 3583) or other similar solution and the SAN
disk and running client backups at the same time.
Paul D. Seay, Jr.
Technical Specialist
Naptheon Inc.
757-688-8180
-----Original Message-----
From: Eliza Lau [mailto:lau AT VTCAT.CC.VT DOT EDU]
Sent: Saturday, August 31, 2002 11:19 AM
To: ADSM-L AT VM.MARIST DOT EDU
Subject: backup performance with db and log on a SAN
I recently moved the 36G TSM database and 10G log from attached SCSI disk
drives to a SAN. Backing the db now takes twice as long as it used to (from
40 minutes to 90 minutes). The old attached disk drives are non-RAID and
TSM mirrored. The SAN drives are RAID-5 and TSM mirrored. I know I have to
pay a penalty for writing to RAID-5. But considering the massive cache of
the SAN it should not be too bad. In fact, performance of client backups
hasn't suffered.
However, the day after the move, I noticed that backup db ran for twice as
long. It just doesn't make sense it will take a 100% performance hit from
reading from RAID-5 disks. Our performance guys looked at the sar data and
didn't find any bottlenecks, no excessive iowait, paging, etc. The solution
is to move the db and log back to where they were. But now management says:
"We purchased this very expensive 2T IBM SAN and you are saying that you
can't use it." Meanwhile, our Oracle people happily report that they are
seeing the performance of their applications enjoy a 10% increase.
Has anyone put their db and log on a SAN and what is your experience? I have
called it in to Tivoli support but has yet to get a callback. Has anyone
noticed that support is now very non-responsive?
server; AIX 4.3.3, TSM 4.2.1.15
Thanks,
Eliza Lau
Virginia Tech Computing Center
1700 Pratt Drive
Blacksburg, VA 24060
lau AT vt DOT edu
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