Re: db writer working data sets

May be of interest
http://forums.oracle.com/forums/thread.jspa?messageID=3528668

On Wed, Jun 3, 2009 at 9:32 AM, Taral Desai <taral.desai@xxxxxxxxx> wrote:

> 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
>



-- 

Thanks & Regards,
Taral Desai
Woody Allen <http://www.brainyquote.com/quotes/authors/w/woody_allen.html>
- "Money is better than poverty, if only for financial reasons."

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