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DB2 - Problem description

Problem IC66765 Status: Closed

ONLINE BACKUP PERFORMANCE SLOW AT if tablespaces have many
containers (Regression)

product:
DB2 FOR LUW / DB2FORLUW / 950 - DB2
Problem description:
Online backup slow compared to previous versions 
if the tablespaces have many containers (typically 32 or more). 
 
A symptom is that the read I/O on the server is not being driven 
intensively. 
 
Analysing stack from a db2pd -stack will show that only 1 of the 
db2 prefetchers (db2pfchr) is doing work, whereas the remainder 
are idle. That is there would be 1 stack similar to the 
following : 
 
 
 Stack: 
 ====================== 
 
 0x090000000006226C pread64 + 0x34 
  0x09000000030036CC sqloReadBlocks + 0x18 
  0x0900000002B94E54 
sqlbReadBlocks__FP16SqlbOpenFileInfoPvlUlUiPUlP12SQLB_GLOBALS + 
0x100 
  0x090000000300D1DC 
@28@sqlbDMSReadContainerData__FP17SQLB_DIRECT_IO_CBP13SQLB_MAP_I 
NFOP16SqlbOpenFileInfoPcP12SQLB_GLOBALS + 0x28 
  0x090000000300CF1C sqlbDMSDirectRead__FP17SQLB_DIRECT_IO_CB + 
0x400 
  0x0900000002B9018C sqlbDirectRead__FP17SQLB_DIRECT_IO_CB + 
0x10C 
  0x090000000390E7AC 
sqlbServiceDirectReadRequest__FP11SQLB_pfMisc + 0x684 
  0x09000000029E7660 sqlbPFPrefetcherEntryPoint__FPcUi + 0x444 
  0x0900000002FB610C 
sqloCreateEDU__FPFPcUi_vPcUlP13SQLO_EDU_INFOPi + 0x268 
  0x0900000002F6956C @49@sqloRunGDS__Fv + 0xDC 
 
with all the other db2 prefetchers having stacks similar to the 
following : 
 
  Stack: 
 ====================== 
 
 0x09000000001D6394 msgrcv + 0xB0 
  0x09000000030850FC .sqloCSemP_fdprpro_clone_929 + 0x144 
  0x0900000003085328 
.sqlbpfRemoveFromQ__FP12SQLB_pfQUEUEUlPP14SQLB_pfRequestP8sqledb 
cbPP12SQLD_OBJ_HDLP12SQLB_GLOBALS_fdprpro_clone_93 + 0x15C 
  0x0900000003085CB0 sqlbPFPrefetcherEntryPoint__FPcUi + 0x100 
  0x0900000002FB610C 
sqloCreateEDU__FPFPcUi_vPcUlP13SQLO_EDU_INFOPi + 0x268 
  0x0900000002F6956C @49@sqloRunGDS__Fv + 0xDC 
  0x0900000002FB4D0C sqloInitEDUServices + 0x178 
  0x0900000002FAED84 
@49@sqloSystemControllerMain__FCUiPFv_iPFi_vPPvCPi + 0x33C 
  0x0900000002FB0438 sqloRunInstance + 0xA8 
  0x00000001000029F8 DB2main + 0x930
Problem Summary:
**************************************************************** 
* USERS AFFECTED:                                              * 
* ALL                                                          * 
**************************************************************** 
* PROBLEM DESCRIPTION:                                         * 
* Same as error description                                    * 
**************************************************************** 
* RECOMMENDATION:                                              * 
* Upgrade to DB2 V 9.5 FP6                                     * 
****************************************************************
Local Fix:
Rearrange the tablespaces so that there are less containers per 
tablespace - typically less than 32.
available fix packs:
DB2 Version 9.5 Fix Pack 6a for Linux, UNIX, and Windows
DB2 Version 9.5 Fix Pack 7 for Linux, UNIX, and Windows
DB2 Version 9.5 Fix Pack 8 for Linux, UNIX, and Windows
DB2 Version 9.5 Fix Pack 9 for Linux, UNIX, and Windows
DB2 Version 9.5 Fix Pack 10 for Linux, UNIX, and Windows

Solution
Problem first fixed in DB2 Version 9.5 Fixpack 6
Workaround
not known / see Local fix
Timestamps
Date  - problem reported    :
Date  - problem closed      :
Date  - last modified       :
01.03.2010
12.07.2010
25.01.2011
Problem solved at the following versions (IBM BugInfos)
9.5.FP6
Problem solved according to the fixlist(s) of the following version(s)
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