|
Problem IC74138
|
Status: Geschlossen |
STMM FAILS TO USE EXCESS MEMORY IN USE BY FILE CACHE ON AIX WITH SMALL PAGING SPACE |
| Produkt: |
DB2 FOR LUW / DB2FORLUW / 970 - DB2 |
| Problembeschreibung: |
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. |
| Problem-Zusammenfassung: |
****************************************************************
* 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. *
**************************************************************** |
| Local-Fix: |
Increase paging space to at least 50% of RAM |
| verfügbare FixPacks: |
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
|
| Lösung |
Problem first fixed in DB2 Version 9.7 Fix Pack 5 |
| Workaround |
n/a |
| Weitere Daten |
Datum - Problem gemeldet :
Datum - Problem geschlossen :
Datum - der letzten Änderung:
| 26.01.2011
27.02.2012
27.02.2012 |
| Problem behoben ab folgender Versionen (IBM BugInfos) |
9.7.FP5
|
| Problem behoben lt. FixList in der Version |
| 9.7.0.5
|
 |
