If you think you disabled Automatic Memory Management in Oracle DB 11.2, think again

Kurt Van Meerbeeck points out the fact that SGA re-sizes are occurring after an upgrade to 11.2 despite the fact that automatic memory management (AMM/ASMM) is disabled via the MEMORY_TARGET and SGA_TARGET parameters being set to zero.

It turns out that this is an expected behavior in 11.2. From Oracle Support note 1269139.1:

Cause:
This is expected behavior in 11.2 for immediate memory allocation requests, which added this as a new feature when automatic memory management was disabled.

Solution:
Ignore the resize operation which is performed to prevent an ORA-4031 error from being raised, or set the parameter _MEMORY_IMM_MODE_WITHOUT_AUTOSGA to false in the instance to disable this feature with the consequence that in future an ORA-4031 error would be raised.

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Filed in Oracle, Tips on 08 Mar 11 | Tags: dba

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