Re: db_writers: Determining appropriate value

On Tue, 30 Jun 1998 19:05:44 GMT, Chuck Hamilton <chuckh_at_dvol.com> wrote:
>I'm running Oracle 7.3.2.3 on HPUX 10.10. What can I query to see if I
>need additional db writers? Perhaps something from v$waitstat or
>v$sysstats?

From docs Tuning Oracle on Solaris book: select * from v$system_event; If there is a value in total_wait, DBWR is a bottleneck. Add writers until there isn't a bottleneck anymore. I don't have an HP system just now, can't verify this applies.

From Ault's O8 book: watch free buffer waits from v$sysstat for spikes when system is busy. Set the DB_WRITERS to the number of disks used by Oracle. Increase _DB_BLOCK_WRITE_BATCH if DBWR performance is still poor, be sure _DB_BLOCK_MAX_SCAN_CNT is 30 or greater.

>
>Oracle Education needs to add this to the tuning class. They tell you
>to use multiple async i/o or multiple db writers - but they don't tell
>you how to determine how many.

Because it's platform specific, application dependent and Async is preferable, I suppose.

>--
>Chuck Hamilton
>chuckh_at_dvol.com
>
>If at first you don't succeed, sky diving isn't for you.

--
These opinions are my own and not necessarily those of Information Quest or Pebble In The Sky http://www.informationquest.com mailto:jgarry@nospameiq.com http://ourworld.compuserve.com/homepages/joel_garry Remove nospam to reply. mailto:joel_garry_at_compuserve.nospam.com "See your DBA?" I AM the @#%*& DBA! Received on Tue Jun 30 1998 - 16:38:06 CDT