Re: Tuning question....

From: <ddf_dba_at_my-deja.com>
Date: 2000/06/22
Message-ID: <8itv7r$ncl$1@nnrp1.deja.com>#1/1

In article <8itsgh$ld3$1_at_nnrp1.deja.com>,   EnderW <ender29_at_my-deja.com> wrote:
> Hi,
> I am probably not gonna get any reply but I should do this on
 general
> principles anyway. I am using the "top" command on a machine and am
> seeing 61% iowait. Now in terms machine is a Solaris 2.7 E4500. Is
 this
> usual ? I have an oracle instance on the machine. I am trying to tune
> it and I have started from system level to see if there is anything I
> can improve. Seems like 61% iowait seems a little high to me. It is
> probably coming from contention from disks. Question is, is this value
> normal for iowait or not ? Thnx...
>
> PS. Better be that group, I don't think sys. adm. are into tuning...
>
> --
> Ender Wiggin
>
> Sent via Deja.com http://www.deja.com/
> Before you buy.
>

My version of 'top' doesn't provide the 'iowait' statistic ( leave it to Sun to provide more info than the rest :) ). If you believe that disk contention is the culprit run the following query:

SELECT file# "FILE_ID",

        phyrds "READS",
        phywrts "WRITES",
        phyblkrd "BLOCK_READS",
        phyblkwrt "BLOCK_WRITES",
        readtim "READ_TIME",
        writetim "WRITE_TIME"

FROM v$filestat;

This should produce a report indicating the activity and the read and write times for the various data files. If you are, indeed, experiencing disk contention it should show up as excessive values in these fields. From there you can map out a plan to eliminate or reduce the contention either by adding disk resource or utilizing the available resource more efficiently.

--
David Fitzjarrell
Oracle Certified DBA


Sent via Deja.com http://www.deja.com/
Before you buy.

Received on Thu Jun 22 2000 - 00:00:00 CDT