DB2 FOR LUW / DB2FORLUW / B10 - DB2

On an STMM-tuned system, when there is a very large memory 
consumer that suddenly becomes idle (in very little need of 
memory), and there is no need to reassign that memory to other 
consumers for a lengthy period (>= 2 hours), STMM may 
subsequently not give memory to other needy consumers (eg. when 
workload ramps up). 
 
This occurs because of conflicting heuristics in STMM's tuning 
model.  A consumer for which historical statistics are "weak" 
will release memory in small amounts.  But those calculated 
amounts may be cancelled out when a separate minimum decrease 
size threshold test is applied. 
 
This situation is rare as the stubborn consumer must be very 
large, the demands of the other consumers modest, and, as stated 
above, there must be a fairly specific and extreme pattern in 
memory demands among the STMM-tuned memory consumers.

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* USERS AFFECTED:                                              * 
* larger systems using STMM (self-tuning memory manager)       * 
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* PROBLEM DESCRIPTION:                                         * 
* See Error Description                                        * 
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* RECOMMENDATION:                                              * 
* upgrade to DB2 Version 11.1 Mod 3 Fix Pack 3                 * 
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Dynamically decrease the configuration of the stubborn large 
consumer in 25% decrements, waiting for ~5 minutes between each 
step before determining if tuning has normalized. 
i.e. 
  db2 connect to <database> 
  db2 alter/update <STMM consumer>... AUTOMATIC

Db2 Version 11.1 Mod 3 Fix Pack 3 for Linux, UNIX, and Windows
 Db2 Version 11.1 Mod3 Fix Pack3 iFix001 for Linux, UNIX, and Windows
 Db2 Version 11.1 Mod3 Fix Pack3 iFix002 for Linux, UNIX, and Windows
 

Problem first solved in DB2 Version 11.1 Mod 3 Fix Pack 3

see Local Fix

Date  - problem reported    :
Date  - problem closed      :
Date  - last modified       :

26.06.2017
15.03.2018
15.03.2018