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

"gc buffer busy", "gc current block busy", "enq: TX- index contention"

- How about you interconnect? Do you use Gigabit NIC?
- Use Partition Table/Index - that can reduce index contention.
- Increase SGA
- Update? - Increase INITRANS
- How about PCTFREE?




Good Luck
Surachart Opun
http://surachartopun.com


On Thu, Dec 24, 2009 at 9:29 PM, Pradeep Chetal <
Pradeep.Chetal@xxxxxxxxxxxxxx> wrote:

>
>
> Thomas,
>
>
>
> There are lot of updates (not inserts) but on some of the tables that are
> populated by sequences and others without sequences.
>
>
>
> I will go through this and see if this helps.
>
>
>
> Thanks,
>
>
>
> -- Pradeep
>
>
>  ------------------------------
>
> *From:* Thomas Roach [mailto:troach@xxxxxxxxx]
> *Sent:* Thursday, December 24, 2009 9:08 AM
> *To:* Pradeep Chetal
> *Cc:* oracle-l@xxxxxxxxxxxxx
> *Subject:* Re: Looking for pointers in troubleshooting -> RAC performance
> degradation (single instance is fine)
>
>
>
> Sorry to early.. meant that it might "NOT" be the right solution for you :)
>
> On Thu, Dec 24, 2009 at 9:07 AM, Thomas Roach <troach@xxxxxxxxx> 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@xxxxxxxxxxxxxx> 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
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>
>
>   --
> Thomas Roach
> 813-404-6066
> troach@xxxxxxxxx
>
>
>
>
> --
> Thomas Roach
> 813-404-6066
> troach@xxxxxxxxx
>
>
> Visit
> *WWW.MFORMATION.COM* and see how the MFORMATION SERVICE MANAGER can help
> you to transform your business
> 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@xxxxxxxxxxxxxx
>

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