slow performance problem

[Keith Bryson · Accepted solution]

Only change the buffer cache setting if glance was calculating wait state for cache at 40%+ (using the glance wait state screen detailed earlier). Only shift it up 100-200Mb then re-test.

Keith

[Ninad_1]

I remember of reading somewhere that sometimes increasing the buffer cache size can degrade performance when using oracle database depending on the application , because the process will be scanning the whole (increased) buffer area each time and hence increased response time .
Is this argument valid ?

Another thing you said that if its showing about 40% on cache wait. i did not see any percentage in the wait for cache screen

[Chris Vail]

REBUILD THE INDEXES! Even, or especially if, the DBA says the indexes are fine, get them rebuilt them anyway. They'll gripe and complain, but you really shouldn't do any Unix tuning until every possible Oracle parameter has been checked, rechecked and checked again.

I've been doing Oracle on Unix since 1993, and this is a lesson I've learned and relearned many times. Every time I've tuned Unix to speed up Oracle, it never meant very much because there was something wrong with Oracle, and usually the indexes. My default response to any speed complaint is that 99.9% of the time, the speed issue is at the application level rather than the OS. Once the OS is tuned to Oracles' spec, you just shouldn't have to mess with it again.

Chris

[Keith Bryson]

Nad

You originally stated that the process WAS waiting for CACHE.

As far as BC affecting performance (in a negative way), that's why I recommended only adding up to 200Mb. I wouldn't go higher than 700-800Mb as this starts to impair system performance and OS filesystem commands (cp, tar etc.).

If this change doesn't alter performance, I can only suggest closer checking of the RAID config, VG/LV config (compare vgdisplay output on both servers - checking VG PE size etc.) and use stm to check for any processor de-allocation (possible) or hardware faults.

All the best - Keith

[Ninad_1]

Thanks for you advice Cris.

Keith,

OK I understand. Thanks a lot for your guidance.

Regs
Nad