Re: gc buffer busy acquire madness

From: Mark Bobak <>
Date: Mon, 9 Dec 2013 18:21:59 +0000
Message-ID: <>


Some thoughts/questions that might get you pointed in the right direction.

'gc buffer busy' usually means you're shipping excessive traffic over the interconnect.

Some questions:

Are you (at least attempting to) isolate/partition your workload, so that specific work runs on a specific RAC node? Are the CPUs really busy? Is there a CPU bottleneck? How large is the SGA? Are you using hugepages?


From: "Nadeem M. Khan" <<>> Reply-To: "<>" <<>> Date: Monday, December 9, 2013 at 12:57 PM To: "<>" <<>> Subject: gc buffer busy acquire madness

Oracle RAC on Linux with two instances prod1 and prod2 When one instance is open, the second instance takes 40 minutes to open from the mount stage. When both instances are open, queries take a long time to complete on prod1 When only one instance is open, queries run normally.

My top 5 waits are:

DAY       EVENT_NAME                                                       TOTAL_WAIT
--------- ---------------------------------------------------------------- ----------
09-DEC-13 gc buffer busy acquire                                               265912
09-DEC-13 gc cr multi block request                                            106042
09-DEC-13 read by other session                                                 54826
09-DEC-13 gc cr block lost                                                       9314
09-DEC-13 DB CPU                                                                 5584
08-DEC-13 gc cr multi block request                                            151110
08-DEC-13 library cache load lock                                                9010
08-DEC-13 DB CPU                                                                 5014
08-DEC-13 gc cr block lost                                                       1668
08-DEC-13 control file sequential read                                           1110
07-DEC-13 gc cr multi block request                                            172730

Has anyone seen this before? Thanks in advance.

Received on Mon Dec 09 2013 - 19:21:59 CET

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