Re: db_writers: Determining appropriate value

We have a Solaris server with 4 cpus and multiple instances. When changing the db_writers in the init.ora file and startup the database, it startups with no problems. But, when I go to the OS and do ps -ef |grep ora_dbwr , I got always one no matter what is the db_writers is in the init.ora.

What could be the problem?.

Thank you

Mamdou Khawaji
DBA In article <slrn6pimpb.m6s.joelga_at_pebble.org>,   joelga_at_nospam.pebble.org wrote:
>
> 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
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>

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