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

This might be a shot in the dark, but with a shotgun, you might hit some target :) In short this looks like an application issue, (or RAC amplifying the application noise).

Treat gc buffer busy (and gc current busy) as you treat the buffer busy waits (or read by other session waits) and tune the storage for the segments accordingly. Techniques like MINIMIZE_RECORDS_PER_BLOCK at segment level or hash partitioning will yield great results.

If you can post the relavant parts from the AWR we can offer a better solution :)(

Happy Holidays and Happy New Year 2010.

Best Regards,
K Gopalakrishnan

Oracle Database 10g Real Application Clusters Handbook http://www.amazon.com/gp/product/007146509X/

Oracle Wait Interface: A Practical Guide to Performance Diagnostics & Tuning http://www.amazon.com/exec/obidos/tg/detail/-/007222729X/

On Thu, Dec 24, 2009 at 7:28 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
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