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Re: Oracle Performance -- Possible Disk Bottleneck

From: Charles Hooper <>
Date: Thu, 07 Jun 2007 20:09:15 -0700
Message-ID: <>

On May 24, 5:56 pm, wrote:
>We've been having performance problems with our Client/Server
>application for months. Users contantly complain of slow response
>times to their queries.

>Here's the environment:
>Oracle 9i on Windows. Poweredge 6850. 4, 3 GHz Quad Core
>Processors. 8 GB RAM. 9i databses are stored on an EMC Clarrion
>CX500 LUN -- RAID 10. 6, 15K 146GB dedicated disks. Oracle logs are
>stored on a separate RAID 10 LUN on dedicated disks. 1 GBE switched
>backend. Users connect using FastEthernet. XP clients. All disks on
>the SAN are fibre channel.

>CPU utilization is fine. RAM utilization is fine. Throughput on the
>NIC is fine -- maxes out at 50 Mbps for a short while when users first
>log in in the morning. Averages are 20 Mbps.

I still do not like sifting through Statspack reports (ever since reading Cary Millsap's book a couple years ago, I prefer other methods). I will pull out a couple items from the report that look interesting:

32 bit Windows with 8GB of memory - it is likely better to stick with 4GB, or jump to 16GB.

The largest wait event of interest:

Event Name                               Count    Total Time
-------------------------------- ------------- -------------
db file sequential read                3742459      2164.09s

A sequential read is a single-block read, where a user process is reading a buffer into the SGA buffer cache and waiting for a physical I/O, usually caused by an index access.

                             Total     Per Tranaction
physical reads             4873242     10047.92
physical reads direct         5328        10.99
recursive calls            1443176      2975.62

Look over the information that appears above. Are there any changes that you can make to the database instance to improve performance?

Charles Hooper
IT Manager/Oracle DBA
K&M Machine-Fabricating, Inc. Received on Thu Jun 07 2007 - 22:09:15 CDT

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