DB2 FOR LUW / DB2FORLUW / 970 - DB2

On AIX, STMM may fail to take away excess system memory from 
file cache, and additionally may tune DB2 down at points when 
most of the system memory is taken up by file cache. 
This occurs only on systems with small paging space 
configurations. 
It will not impact environments using a fixed INSTANCE_MEMORY 
value (STMM does not monitor system memory in this 
configuration). 
Various symptoms may be observed, including erratic STMM tuning, 
performance degradation, and SQL1218 errors (no pages available 
in bufferpool). 
 
The problem is caused by DB2 capping the file cache it sees as 
available by the amount of available paging space. 
DB2 will deduct from this "capped available file cache" amount 
allowances for uncommited DB2 memory, such as unused Utility 
Heap.  The result may be that DB2 / STMM sees the system as 
memory constrained when it is not. 
 
It is recognized that modern well-tuned AIX systems (AIX 5.3 and 
higher) where memory requirements do not exceed capacity do not 
require large paging space configurations, and therefore, under 
normal operating conditions, available paging space should not 
be a limiting factor in the "available file cache" calculation. 
 
The workaround is to increase paging space to at least 50% of 
RAM.

**************************************************************** 
* USERS AFFECTED:                                              * 
* DB2 servers on AIX with self-tuning of database memory       * 
* enabled and no Instance Memory limit (SELF_TUNING_MEM=ON,    * 
* DATABASE_MEMORY=AUTOMATIC, INSTANCE_MEMORY=AUTOMATIC)        * 
**************************************************************** 
* PROBLEM DESCRIPTION:                                         * 
* See Error Description                                        * 
**************************************************************** 
* RECOMMENDATION:                                              * 
* Avoid problem by following documented minimum paging space   * 
* recommendations.                                             * 
****************************************************************

Increase paging space to at least 50% of RAM

DB2 Version 9.7 Fix Pack 5 for Linux, UNIX, and Windows
 DB2 Version 9.7 Fix Pack 6 for Linux, UNIX, and Windows
 DB2 Version 9.7 Fix Pack 7 for Linux, UNIX, and Windows
 DB2 Version 9.7 Fix Pack 8 for Linux, UNIX, and Windows
 DB2 Version 9.7 Fix Pack 9 for Linux, UNIX, and Windows
 DB2 Version 9.7 Fix Pack 9a for Linux, UNIX, and Windows
 DB2 Version 9.7 Fix Pack 10 for Linux, UNIX, and Windows
 

Problem first fixed in DB2 Version 9.7 Fix Pack 5

n/a

Datum - Problem gemeldet    :
Datum - Problem geschlossen :
Datum - der letzten Änderung:

26.01.2011
27.02.2012
27.02.2012

9.7.FP5