System + Wait i/o Utilization

[leemcallister]

Trying to validate some measurements w/our p680 12 cpu running Oracle Appliactions 11i. We are consistently seeing cases where wait i/o + system utilization is > user cpu %. User rarely gets above 40% but at these times the box is only 10% idle due to wait + system. Is this unusual? Should I be drilling into this?

any insight appreciated.

Lee

 

[Yegolev]

The 40% user is probably OK, but it would not hurt to look into disk layout. I am not familiar with Oracle, uh, 11i? Is this a db server or an application server? Perhaps someone with more experience with perf tuning knows. IBM Certified -- AIX 4.3 Obfuscation

 

[Chapter11]

From what I've seen on my machines, a lot of Oracle (db or financials activity) sometimes ends up being listed under "system" because it's doing stuff through its kernel extension (post-wait syscall).

Apart from that, there's not really a "good" way to run OF except not to run it. It's a beast.

 

[leemcallister]

Thanks for the info guys. Some more detail:

1/ Disk is Fibre attached - ESS.
2/ And yes this is the db server.

We have spent a not insiginificant amount of time tuning the Apps SQL and have managed to get that down to something reasonable hence 40% user.

Any idea how I can drill into whether or not it is the post-wait driver causing the high system cpu %?

thanks again for the feedback.

 

[Yegolev]

I would say that if you are only running Oracle then there you go. Oracle is just a hog. We have a machine running Oracle plus SAP and a few bolt-ons (Maestro, etc), and Oracle alone is consuming at least 80% of the current CPU usage.

Grats on looking at the SQL, some people always assume it is an AIX problem. IBM Certified -- AIX 4.3 Obfuscation