Re: db writer working data sets

  • From: Taral Desai <taral.desai@xxxxxxxxx>
  • To: Greg Rahn <greg@xxxxxxxxxxxxxxxxxx>
  • Date: Wed, 3 Jun 2009 09:32:59 -0500

Also sorry it's my bad forgot to include vital information. DB is 10.2.0.3
and OS is solaris 10 sparc 64 bit. We are using SAN for storage

On Wed, Jun 3, 2009 at 9:14 AM, Taral Desai <taral.desai@xxxxxxxxx> wrote:

> 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@xxxxxxxxxxxxxxxxxx>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@xxxxxxxxx>
>> 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
>



-- 

Thanks & Regards,
Taral Desai

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