DB2 FOR LUW / DB2FORLUW / 970 - DB2

DB2 overrides certain kernel tunables in startup to try to 
ensure smooth operation of the DB2 Database Server.  This avoids 
putting the burden of tuning the kernel on DB2/Linux 
administrators. 
Many default limits are too low for DB2's requirements, and some 
limits are unnecessary, especially given the difficulty of 
finding some correct range/value based on peak workload (which 
may change in the future).  The Linux kernel itself alters it's 
approach to default settings at different levels (one example is 
shmall, the total shared memory limit, which is now set so high 
by default that it can be considered virtually unlimited). 
 
. 
DB2's current strategy for overriding kernel limits is not based 
on the size of machines.  As a result, as machines have gotten 
larger, the override values (eg. shmmax, shmall, kernel.sem) are 
not larger enough to prevent unnecessary errors for DB2 
installations.  In addition, in some configurations DB2 version 
9.5 may require a larger virtual shared memory space (not "real" 
memory), resulting in a larger shmall requirement. 
 
. 
This APAR will both update the override values to take into 
account larger machines AND update the standard DB2 
documentation, which currently does not state that DB2 overrides 
default/low settings.

**************************************************************** 
* USERS AFFECTED:                                              * 
* All DB2 on Linux systems                                     * 
**************************************************************** 
* PROBLEM DESCRIPTION:                                         * 
* See Error Description                                        * 
**************************************************************** 
* RECOMMENDATION:                                              * 
* If running on older DB2 levels, it is recommended tomanually * 
* set kernel parameter settings to the updatedvalues.This is   * 
* especially important for new installations on largersystems  * 
* (eg. 16GB RAM or higher) or where increasingworkload.        * 
****************************************************************

Update kernel tunables manually. 
See current documentation for recommendations.

DB2 Version 9.7 Fix Pack 2 for Linux, UNIX, and Windows
 DB2 Version 9.7 Fix Pack 3 for Linux, UNIX, and Windows
 DB2 Version 9.7 Fix Pack 3a for Linux, UNIX, and Windows
 DB2 Version 9.7 Fix Pack 4 for Linux, UNIX, and Windows
 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 9a for Linux, UNIX, and Windows
 DB2 Version 9.7 Fix Pack 9 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 2

not known / see Local fix

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

03.06.2009
14.06.2010
15.07.2010

9.7.FP2