Info AIX 4, Sybase and SSA disk array problem

Info AIX 4, Sybase and SSA disk array problem

Post by asif kale » Sat, 26 Oct 1996 04:00:00

Hello everyone:

This posting is just for information:

We recently bought SSA disk array from IBM for our RS/6000 box. Recently
started using the disk using for Sybasee 4.9.2.  Disk init on the raw
partition works ok but as soon as you put a database on it we see quite a
few problems. Most often database is corrupted with page link errors.
Some time the whole database will be gone.

After investigating we found out that with disk array appliction who are
using raw partitions and uses less than 4k buffers should faces problem
with ssa disk driver algorithm.  There is a problem with the Miscompress seen
by the application which is in our case is sybase.


This problem is solved by appling a patch from IBM/AIX 4.1.4. The PTF number
for this patch is U440347.  This patch is available through IBM web page.

if you are facing this problem try using the search engine at ibm site to
find the exact location for the patch.

or Send me an email and I will gladly mail it to you.

Thanks :-)

Asif Kaleem               _/    _/ _/    _/  _/_/_/    
Technical Services       _/    _/ _/    _/ _/    _/  AT&T: (612) 945-6846
United HealthCare Corp. _/    _/ _/_/_/_/ _/         Fax:  (612) 945-6643

Minnetonka, MN 55343   _/_/_/  _/    _/  _/_/_/


1. Performance Problem w/ Sybase on HP-UX Disk Array Model 20

We have installed a HP model 20 disk array on a HP9000-T500 running hp-ux 9.04.
We have tried multiple configurations such as raid 0, raid 1/0 and raid 5 and
for all of the configurations Sybase10.02 is 100% slower when doing a "dbcc
checkdb" versus the non-raid fast and wides.  On the other hand the bcp's with
all the possible configurations take the same amount of time.  The only time
that we managed to increase the performance of the dbcc is when we created a
file system on the array. Though this seems to be the only option, it is not a
solution since we can not have a database on a file system.

My understanding is that this particular disk array is fairly new and "should"
function a lot better with hp-ux 10, but meanwhile I would appreciate to hear if
anyone has had a similar problem and if there is a resolution to it..

Thanx in advance

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