Re: Looking for pointers in troubleshooting -> RAC performance degradation (single instance is fine)

On Thu, Dec 24, 2009 at 9:07 AM, Thomas Roach <troach_at_gmail.com> wrote:

> Hi,
>
> Are you doing a lot of inserts/updates to tables that have indexes that are
> populated by sequences? You should find the objects the contention is on. To
> assist with this, take a look at this page.
> http://www.ardentperf.com/2007/09/12/gc-buffer-busy-waits-in-rac-finding-hot-blocks/
>
> Basically what "could" be happening (what happened with me) was that I had
> a bunch of sessions across nodes all fighting to put entries into the same
> index blocks. Even on one node, this would be a contention issue. What I did
> to fix my issue was identify the indexes with the contention and made them
> reverse key indexes. With reverse key indexes you lose the ability to
> perform certain operations like an index range scan. So if you do queries
> where something is between this value and that value etc, it might be the
> right solution for you.
>
> Good Luck.
>
>
>
>
> On Thu, Dec 24, 2009 at 8:28 AM, Pradeep Chetal <
> Pradeep.Chetal_at_mformation.com> wrote:
>
>>
>>
>> Folks,
>>
>>
>>
>> We have an app that is running well in single instance but when put on a
>> 2-node or 3-node RAC, we see pretty much similar performance. However, if
>> the CPU time is 55-60% in single instance, it becomes 20% in 3-node RAC and
>> top-5 itmed events become..
>>
>>
>>
>> "gc buffer busy", "gc current block busy", "enq: TX- index contention
>>
>>
>>
>> Any help in what to look for will be greatly appreciated.
>>
>>
>>
>> Thanks,
>>
>>
>>
>> -- Pradeep
>>
>> *Pradeep Chetal*
>> Sr. Director - Infrastructure Architecture
>> ------------------------------
>> *Mformation Technologies Inc.*
>> *Switchboard:* +1 732 692 6200
>>
>>
>> Visit
>> *WWW.MFORMATION.COM* and see how the MFORMATION SERVICE MANAGER can help
>> you to transform your business
>>
>> Please consider the environment before printing
>> This message and the information contained herein is proprietary and
>> confidential and subject to the Mformation Confidentiality policy
>> statement,
>> you may request a copy by emailing info_at_mformation.com
>>
>
>
>
> --
> Thomas Roach
> 813-404-6066
> troach_at_gmail.com
>

-- 
Thomas Roach
813-404-6066
troach_at_gmail.com

--
http://www.freelists.org/webpage/oracle-l