DB File Sequential Reads

From: <Rajesh.Rao_at_jpmchase.com>
Date: Thu, 07 Feb 2002 09:45:18 -0800
Message-ID: <F001.004091BB.20020207093324@fatcity.com>

Hi Fellas,

An old SIEBEL application running against a 7.3.4 database on NT. There are performance issues. A query which runs with in no time on the QA box, takes 2 minutes on the production. Optimizer is set to RULE. The access plan is the same on both the boxed for the query. On Production, V$waitstat showed me lots of waits for 'data blocks', v$system_event showed me waits for 'db file sequential reads' and 'buffer busy waits'. From v$session_wait, I tracked this down to a single table. v$filestat shows me lot of physical reads for the disk where the datafile holding that table resides. The same table is spread across two datafiles on different drives on the QA, whereas its spread across a single drive on Production. Increasing the free lists on the table is also an option I am considering. What I would also like to know is:

How do you monitor I/O activity on an NT Server? Something like sar -d or iostat on Unix?
The status is 'WAITING' in v$session_wait, but seconds_in_wait is 0. Is it because TIMED_STATISTICS is set to FALSE?

Thank You for your help.

Raj

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