Re: Oracle8.1.7 : Very high CPU load but NO alert.log record

On May 5, 10:13 am, "jshen...._at_gmail.com" <jshen...._at_gmail.com> wrote:
> Hi,
>
>    two of our DB server suffered very high CPU load today. we could
> not identify the exact reason
> for it.
>
>    We run a main DB whose table content update frequently.  Both of
> the two questionable servers maintein Snapshot of  main DB,  they
> refresh snapshot every 5 min. The OS of two stallite server is HP UX
> 11i.  Normally, the two stalitte servers' CPU is just around 20%.
>
>    Today,  both of them run suffered very high CPU load (around 96%
> and above), application on stalite DB respond very slow with a lot of
> service timeout.  we have to stop the application  which make the two
> stallite DB CPU come back within 20min. Restarting application does
> not generate the same problem at all.
>
>    Looking into sar ball stored, we just find there is high CPU and a
> lot of semops. But there is NO alert.log record and Archive was
> executed successfully.
>
>    What's the possible reason for this ?
>
>    sar record information:
>

This is only half of it. You need to ask Oracle what it thinks it is waiting for. It could be something simple, or something convoluted like a problem with your I/O that makes the Oracle concurrency methods spin the cpu. See the performance manual at tahiti.oracle.com, as well as the book by Cary Milsap. Of course, being on such an old Oracle it could be something that is easily solved with the more modern way things are done nowadays, but not so easy the old ways.

Two things you might do, run statspacks (described in the docs), and check how many extents are in your FET$ table (google for scripts).

jg

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