DB2 FOR LUW / DB2FORLUW / 980 - DB2

Customers with large DPF environments are experiencing 
significant performance issues and apparent hangs due to 
contention when FCM resources are tuned automatically. The 
system controller thread (db2sysc) will adjust FCM resources 
downward after 30 minutes or more of low workload. During 
relatively quiet times, the resources can get adjusted down to 
very low values. This causes problems on systems with large 
workload bursts. When the workload increases dramatically, the 
FCM resources need to be adjusted upwards quickly and this is 
when performance issues due to latch contention in the dynamic 
adjustment code occurs. This problem gets worse on large DPF 
instances with many logical partitions configured.

**************************************************************** 
* USERS AFFECTED:                                              * 
* All DB2 users                                                * 
**************************************************************** 
* PROBLEM DESCRIPTION:                                         * 
* Control dynamic downward adjustment of FCM resources         * 
**************************************************************** 
* RECOMMENDATION:                                              * 
* Upgrade to DB2 V9.8 FP5                                      * 
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Large DPF customers can set FCM resources to large fixed values. 
However, the downside is that this may cause node failures in 
cases when db2fcmr/db2fcms EDUs run out of FCM buffers/channels.

DB2 Version 9.8 Fix Pack 4 for AIX and Linux
 DB2 Version 9.8 Fix Pack 5 for AIX and Linux
 

Customers with large DPF environments like are experiencing 
significant performance issues and 
apparent hangs due to contention when FCM resources are tuned 
automatically. The system 
controller thread (db2sysc) will adjust FCM resources downward 
after 30 minutes or more of low 
workload. During relatively quiet times, the resources can get 
adjusted down to very low values. 
This causes problems on systems with large workload bursts. When 
the workload increases dramatically, 
the FCM resources need to be adjusted upwards quickly and this 
is when performance issues due to latch 
contention in the dynamic adjustment code occurs. This problem 
gets worse on large DPF 
instances with many logical partitions configured.

not known / see Local fix

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

01.05.2010
30.11.2011
30.11.2011

9.8.FP5