DB2 FOR LUW / DB2FORLUW / A10 - DB2

This is an infrequent timing issue that can only happen if the 
following conditions are true: 
 
1) STMM altering a buffer pool 
2) Online database backup has started. As the result of this, 
dirty pages from the same buffer pool are being written out to 
the disk (the buffer pool is being flushed) 
3) Page cleaners are paused by STMM 
 
An optional condition making the problem worse is: 
 
4) The TRACKMOD DB CFG configuration parameter is enabled 
 
Under these conditions, the buffer pool flush may take a long 
time (even hours or longer, depending on the number of dirty 
pages that need to be written out), which the end user may 
perceive as a hang. The user will not be force off the running 
backup during this time. The following symptoms will be seen: 
 
ad 1) STMM altering a buffer pool: 
EDU "db2stmm" waiting for the 
"SQLO_LT_SQLB_BufferPool__prevBPDCachingLatch" latch. The call 
stack for this EDU will have the "sqlbFinalizeRTBPState" eye 
catcher present on the stack, usually similar to: 
 
getConflictComplex 
getConflict 
sqlbFinalizeRTBPState 
sqlbAlterBufferPoolAct 
sqlbAlterAutomaticBufferPool 
sqlrlStmmAlterBufferPool 
stmmAlterBufferPool 
 
ad 2) Online backup flushing the same buffer pool: 
The owner of "SQLO_LT_SQLB_BufferPool__prevBPDCachingLatch" will 
be "db2bm". This EDU will be flushing the buffer pool. Call 
stacks taken in several iterations will reveal this EDU in 
various phases of writing out dirty pages, typically during file 
system write operations. If TRACKMOD enabled, the flush will 
take even longer because we will need to write more dirty pages 
than with TRACKMOD disabled. An example call stack will contain 
"sqlbFlushFull": 
 
pwrite64 
sqloseekwrite64 
sqloWriteBlocks 
sqlbWriteBlocks 
sqlbWritePageToDisk 
sqlbWritePage 
sqlbFlushForDLSubset 
sqlbFlush 
sqlbFlushFull 
sqlubBMCont 
sqlubbuf 
 
ad 3) Page cleaners paused 
All the page cleaners ("db2pclnr" EDUs) will be paused. Their 
call stack will show "sqlbClnrCheckAndPause", for example: 
 
semtimedop 
sqloWaitEDUWaitPost 
sqlbClnrCheckAndPause 
sqlbClnrFindWork 
sqlbClnrEntryPoint 
sqbPgClnrEdu

**************************************************************** 
* USERS AFFECTED:                                              * 
* Users prior to DB2 V10.1                                     * 
**************************************************************** 
* PROBLEM DESCRIPTION:                                         * 
* See Error Description                                        * 
**************************************************************** 
* RECOMMENDATION:                                              * 
* Upgrade to DB2 V10.1 FP1                                     * 
****************************************************************

1) Alter the buffer pool, making it non-automatic (manual), i.e. 
not tunable by STMM, OR 
2) Take an offline backup if possible

DB2 Version 10.1 Fix Pack 1 for Linux, UNIX, and Windows
 DB2 Version 10.1 Fix Pack 2 for Linux, UNIX, and Windows
 DB2 Version 10.1 Fix Pack 3 for Linux, UNIX, and Windows
 DB2 Version 10.1 Fix Pack 4 for Linux, UNIX, and Windows
 DB2 Version 10.1 Fix Pack 3a for Linux, UNIX, and Windows
 DB2 Version 10.1 Fix Pack 6 for Linux, UNIX, and Windows
 

First Fixed in DB2 V10.1 FP1

not known / see Local fix

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

12.06.2012
02.11.2012
02.11.2012