|
Problem IC83974
|
Status: Closed |
AUTOMATIC TUNING OF LINUX KERNEL.SHMALL PARAMETER INCORRECTLY ASSUMES THAT PAGE SIZE IS 4K |
| product: |
DB2 FOR LUW / DB2FORLUW / 970 - DB2 |
| Problem description: |
Starting in DB2 9.7 Fix Pack 2 and DB2 9.5 Fix Pack 6, the
database manager uses a new formula to automatically adjust
kernel parameter settings:
kernel.shmall (SHMALL) = 2 * <size of RAM in 4k pages>
During the starting of the DB2 instance, DB2 on Linux updates
the kernel parameter SHMALL to a size equal to double the size
of RAM. However in this calculation DB2 assumes the Linux
default memory page size is equal to 4k. This assumption is not
correct on a system where the default memory page size is not
4k, such as on a system with
a 64k page size.
As a result , the calculated kernel parameter shmall may be too
big. Please note that this fact itself doesn't cause any problem
for DB2, and the instance should start normally.
The formula has been adjusted as follows:
kernel.shmall (SHMALL) = 2 * <size of RAM in the default
system page size> |
| Problem Summary: |
****************************************************************
* USERS AFFECTED: *
* DB2FORLUW *
****************************************************************
* PROBLEM DESCRIPTION: *
* Starting in DB2 9.7 fixpack 2 and DB2 9.5 fixpack 6, the *
* database manager uses a new formula to automatically adjust *
* kernel parameter settings: *
* *
* kernel.shmall (SHMALL) = 2 * <size of RAM in 4k pages> *
* *
* During starting the DB2 instance, DB2 on Linux updates the *
* kernel parameter shmall to size equal to double sizes of *
* RAM. In this calculation DB2 assumes the Linux default *
* memory page size equal to 4k. This assumption is not correct *
* on a system where the default memory page size is not 4k, *
* such as on a system with 64k page size. *
* *
* As a result , the calculated kernel parameter shmall is too *
* big. Please note that this fact itself doesn't cause any *
* problem for DB2, and the instance should start normally. *
* *
* The formula has been adjusted as follows: *
* kernel.shmall (SHMALL) = 2 * <size of RAM in the default *
* system page size> *
****************************************************************
* RECOMMENDATION: *
* Upgrade to DB2 9.7 fixpack 7 *
**************************************************************** |
| Local Fix: |
|
| available fix packs: |
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
|
| Solution |
|
| Workaround |
not known / see Local fix |
| BUG-Tracking |
forerunner : APAR is sysrouted TO one or more of the following: IC86813 IC88344
follow-up : |
| Timestamps |
Date - problem reported :
Date - problem closed :
Date - last modified :
| 06.06.2012
23.10.2012
23.10.2012 |
| Problem solved at the following versions (IBM BugInfos) |
9.7.FP7
|
| Problem solved according to the fixlist(s) of the following version(s) |
| 9.7.0.7
|
 |
