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Home -> Community -> Mailing Lists -> Oracle-L -> RE: Reducing sga_target in 10gR2 without getting ORA-00827
We had significant problems with sga_target, enough that we finally
turned it off. Apparently, in 10.2.0.1 there are some issues with the
algorithm that allocates/deallocates memory which can cause degradation.
Our Support Analyst(s) referenced the following bugs: 4466399/4472338 (dup) (SR 5386579.993): SYSTEM WIDE HANG ON MMON WAITING FOR 'SGA ALLOCATION FORCING COMPONENT GROWTH': 4507532 (SR 5256243.992): SGA_TARGET DOESN'T WORK AS EXPECTED Not sure if this is relevant for your situation, but wanted to offer it up just in case.
-----Original Message-----
From: oracle-l-bounce_at_freelists.org
[mailto:oracle-l-bounce_at_freelists.org] On Behalf Of Michael Ray
Sent: Friday, June 16, 2006 9:31 AM
To: oracle-l_at_freelists.org
Subject: Reducing sga_target in 10gR2 without getting ORA-00827
To attempt to mitigate ORA-04030 crashes we've been experiencing, Oracle has suggested lowering sga_target. Unfortunately, the log/trace files have provided no clues at all as to what is causing this crash every 3-5 weeks. The server has 4GB of physical RAM, but is not using the /3GB switch so Oracle can only access 2GB. Currently sga_target is set at 1.2GB. The server runs only this 1 instance of Oracle so Windows has plenty of mem.
select * from v$sga_dynamic_free_memory gives 0 because sga_target=sga_max_size so Oracle has no memory to grow if needed. It shouldn't need to since 1.2GB should be way more mem than it needs for SGA. Based on note 295626.1 I don't think I can reduce sga_target appreciably without getting ORA-00827 (could not shrink sga_target to specified value). Currently the sum of the min sizes
(select component, current_size/1024/1024 "CURRENT_SIZE",
min_size/1024/1024 "MIN_SIZE", user_specified_size/1024/1024 "USER_SPECIFIED_SIZE"from v$sga_dynamic_components)
is 1188 and sga_target is 1200.
Is there any way I can reduce sga_target to 1000 dynamically? Will I just have to keep doing it in small steps of 12 for example?
--
Sincerely,
Michael Ray
Topshot Systems LLC
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Received on Fri Jun 16 2006 - 09:54:08 CDT
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