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DB2 - Problem description

Problem IC81190 Status: Closed

DB2 LOGGER I/O CONTENTION CAUSING PERFORMANCE ISSUES

product:
DB2 FOR LUW / DB2FORLUW / 970 - DB2
Problem description:
If LOGBUFSZ database configuration parameter is set to a high 
value, then contention can be seen during db2 logging since 
db2ReadLog API would be called repeatedly which can stress 
memory and cause performance issues on busy systems. 
 
db2pd -latches output will show db2 loggers waiting for the 
following latch: 
 
Latches: 
Address            Holder     Waiter     Filename 
LOC        LatchType 
No latch holders. 
0x07000000700003E0 0          1135675    Unknown              45 
SQLO_LT_SMemPool__MemLatchType__latch 
0x07000000700003E0 0          1137474    Unknown              45 
SQLO_LT_SMemPool__MemLatchType__latch 
0x07000000700003E0 0          1138759    Unknown              45 
 
0x0700000040027300 0          2316429    Unknown 
189        SQLO_LT_SQLP_APPEND_LREC_CB_IO__logIOCompLatch 
0x0700000040027300 0          102817     Unknown 
189        SQLO_LT_SQLP_APPEND_LREC_CB_IO__logIOCompLatch 
 
The stack dumps for the db2logger process may look as follows: 
 
0x09000000000EEEF8 thread_wait + 0x98 
  0x090000000DAB775C getConflictComplex__17SQLO_SLATCH_CAS64FCUl 
+ 0x3DC 
  0x090000000DAB7ABC getConflict__17SQLO_SLATCH_CAS64FCUl + 0xC8 
  0x090000000DAB7BA0 getConflict__17SQLO_SLATCH_CAS64FCUl@glueF9 
+ 0x74 
  0x090000000DA00FCC 
sqlpProcessWakeUpList__FP9SQLP_DBCBP22SQLP_APPEND_LREC_CB_WA + 
0x20 
  0x090000000DB3AA10 sqlpgasn2__FPcUi + 0x100 
  0x090000000DC8FBB8 sqloEDUEntry + 0x36C
Problem Summary:
**************************************************************** 
* USERS AFFECTED:                                              * 
* All users on DB2 v97 FP5 and earlier                         * 
**************************************************************** 
* PROBLEM DESCRIPTION:                                         * 
* See Error Description                                        * 
**************************************************************** 
* RECOMMENDATION:                                              * 
* Upgrade to DB2 v97 FP6                                       * 
****************************************************************
Local Fix:
As a temporary workaround, you may try reduce LOGBUFSZ a little 
and verify. The size has to be chosen carefully as too 
small 
value can cause performance impacts as well for a busy system. 
Hence, the value needs to be carefully chosen as per workloads 
on the system.
available fix packs:
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

Solution
First Fixed in DB2 v97 FP6
Workaround
not known / see Local fix
Timestamps
Date  - problem reported    :
Date  - problem closed      :
Date  - last modified       :
02.02.2012
26.06.2012
12.07.2012
Problem solved at the following versions (IBM BugInfos)
9.7.FP6
Problem solved according to the fixlist(s) of the following version(s)
9.7.0.6 FixList