Re: db writer working data sets

From: Taral Desai <taral.desai_at_gmail.com>
Date: Wed, 3 Jun 2009 09:14:09 -0500
Message-ID: <2b0cd5cd0906030714h4dcb49dfmb3e6e50291311aeb_at_mail.gmail.com>

Thanks Greg,
I got your point. Well, what about my first 2 questions. How do i find that information.

On Wed, Jun 3, 2009 at 12:35 AM, Greg Rahn <greg_at_structureddata.org> wrote:

> Unless "free buffer waits" is in your top 5 wait events in
> AWR/Statspack, you dont need more db writers. In almost all cases,
> the default value for db_writer_processes is sufficient.
>
> http://download-west.oracle.com/docs/cd/B28359_01/server.111/b28274/instance_tune.htm#sthref759
>
> Tuning "buffer busy waits" is different. You need to find out what
> what type of buffer is being waited for and triage why.
>
> http://download-west.oracle.com/docs/cd/B28359_01/server.111/b28274/instance_tune.htm#sthref657
>
> As a data point, the recent TPC-C that Oracle published
> http://tpc.org/tpcc/results/tpcc_result_detail.asp?id=109052101
> used a db server that has 72GB RAM, multiple block caches (2k/8k/16k)
> and 1 CPU (quad core Intel 5520 "Nehalem") and did over 230k tpmC
> using a single db writer.
>
> On Tue, Jun 2, 2009 at 2:50 PM, Taral Desai <taral.desai_at_gmail.com> wrote:
> > Reason behind this we are using 12 dbwriter process for we have 12gb of
> sga
> > and 10gb of pga. Some time we are getting buffer busy waits. So, need to
> > find that we are using multiple buffer pools. So, if it is from there
> then i
> > can suggest management to use only default block size and not multiple. I
> > already know that multiple buffer pool have overhead
> > of managing one more memory structure so need to investigate and learn
> from
> > you.
> > My idea is to reduce this and then start adding processes if necessary.
>
>
> --
> Regards,
> Greg Rahn
> http://structureddata.org
>

-- 

Thanks & Regards,
Taral Desai

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Received on Wed Jun 03 2009 - 09:14:09 CDT