Database peformance after switching to CIO

From: -A <>
Date: Thu, 24 Apr 2008 16:18:21 -0700 (PDT)
Message-ID: <>

OS - AIX 3
Oracle -

We recently switched over from async IO to CIO. [filesystemio_options to setall]
Reason for this move was a lot of log buffer and log sync waits. Contrary to the expectation, we have noticed performance degradation in our batch jobs.

System Event 		Total Waits 	Timeouts 	Time Waited
db file sequential read		234,932,597	0	516,917
db file scattered read		104,119,285	0	218,360
rdbms ipc message		38,010,738	1,642,294	5,860,312
PX Deq: Execution Msg	31,088,553	105,763	237,518
PX Deq: Execute Reply	24,608,715	2,489	84,274
direct path read		22,753,359	0	92,395
PX Deq: Table Q Normal	19,672,286	16,399	66,533
buffer busy waits		19,514,194	5,524	55,345

Though log buffer and log sync waits have disappeared, but sequential read and scattered read waits have increased. One recommendation that came forward was to increase db cache size. Reason behind this was as there is no OS level caching with CIO and oracle needs to manage it, we need a large db cache size.

I just wanted to know if anyone has run into a similar situation and if increasing db cache size is the right direction.

Atul Received on Thu Apr 24 2008 - 18:18:21 CDT

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