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Performance diminishes over time on AIX 7.1 due to Large Segment Aliasing (Doc ID 1467807.1)

Last updated on AUGUST 04, 2018

Applies to:

Oracle Server - Enterprise Edition - Version 10.2.0.1 to 11.2.0.3 [Release 10.2 to 11.2]
IBM AIX on POWER Systems (64-bit)

Symptoms

Database performance progressively degrades over time until the instance is restarted.
This could manifested by seeing the same SQL, with the same number of buffer get, s gradually  taking more and more CPU time, thereby increasing the overall elapsed time.  


This addition to CPU will show up under sys time and not user time as shown in the vmstat information bleow:

 

Changes

This problem may be seen after migration to AIX 7.1 from lower versions of the OS.
It will usually only be experienced in RDBMS 11.2.0.3 as a result of a code change that helped to  expose the issue.
RDBMS 11.2.0.2 and lower will not be likely to experience the same performance issue

Cause

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In this Document
Symptoms
Changes
Cause
Solution
References

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