Comments on: GC Buffer Busy Waits in RAC: Finding Hot Blocks

By: baskar.loganathan

baskar.loganathan — Wed, 03 Mar 2010 03:35:43 +0000

Excellent article and wonderful explanation…

thanks,
baskar.l

By: Unni

Unni — Wed, 24 Feb 2010 15:45:51 +0000

Well presented research work! Thank you for sharing!
For 16k or higher block size, if we increase the PCTFREE would reduce the number of rows per block, may reduce the gc buffer busy waits. I will try this step and let you know. the default value of PCTFREE is 10, may want to change to 40 in a 16k block. Not sure this will work but I will give it a try.

Unni Kirandumkara.

By: IsleOracle

IsleOracle — Wed, 10 Feb 2010 22:05:00 +0000

Jeremy – Thanks for the walk through – we ran into the same problem (9.2.0.8).

My recommendation was to reduce the block size from 8k to 2k.
Thus reduce the number of rows per block and block contention.

IsleOracle

By: Prem

Prem — Tue, 19 Jan 2010 16:48:42 +0000

Excellent drill down Jeremy. I’m just waiting for a “GC Buffer Busy Wait” in my RAC instance :)

~ jp ~

By: Jammula

Jammula — Wed, 30 Dec 2009 06:34:54 +0000

Perefct.

This is the greatest article which i ever gone through related to this topic. Appreciate for your time.

By: ershad

ershad — Sun, 13 Dec 2009 11:16:59 +0000

I am facing the same issue but space management is also set to auto.
So , what should be my next workaround from here.

For me, the wait is on 2 tables (75%) AND DEPENDENT INDEXES(25%).

thanks,
Ershad

By: Praveen

Praveen — Thu, 19 Nov 2009 06:23:57 +0000

Man, thank you very much for explaining your flow of ideas to identify bottlenecks. i will really look forward for such an approach in my work to come.

Thank you again :)

By: Mehmoo

Mehmoo — Sun, 15 Nov 2009 10:41:54 +0000

very nice and intelligent post, keep it up buddy.

cheers

By: Jay A

Jay A — Fri, 26 Jun 2009 05:33:06 +0000

Great Post.
Got the same problem, and now I have something to start with.

By: adarsh Kumar

adarsh Kumar — Thu, 18 Jun 2009 20:03:26 +0000

I love this article
very nice