IBM Support

IC66765: ONLINE BACKUP PERFORMANCE SLOW AT if tablespaces have many containers (Regression)

Subscribe

You can track all active APARs for this component.

 

APAR status

  • Closed as program error.

Error 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
    

Local fix

  • Rearrange the tablespaces so that there are less containers per
    tablespace - typically less than 32.
    

Problem summary

  • ****************************************************************
    * USERS AFFECTED:                                              *
    * ALL                                                          *
    ****************************************************************
    * PROBLEM DESCRIPTION:                                         *
    * Same as error description                                    *
    ****************************************************************
    * RECOMMENDATION:                                              *
    * Upgrade to DB2 V 9.5 FP6                                     *
    ****************************************************************
    

Problem conclusion

  • Problem first fixed in DB2 Version 9.5 Fixpack 6
    

Temporary fix

Comments

APAR Information

  • APAR number

    IC66765

  • Reported component name

    DB2 FOR LUW

  • Reported component ID

    DB2FORLUW

  • Reported release

    950

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2010-03-01

  • Closed date

    2010-07-12

  • Last modified date

    2011-01-25

  • APAR is sysrouted FROM one or more of the following:

    IC66669

  • APAR is sysrouted TO one or more of the following:

Fix information

  • Fixed component name

    DB2 FOR LUW

  • Fixed component ID

    DB2FORLUW

Applicable component levels

  • R950 PSN

       UP

[{"Business Unit":{"code":"BU048","label":"IBM Software"},"Product":{"code":"SSEPGG","label":"DB2 for Linux, UNIX and Windows"},"Component":"","ARM Category":[],"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"9.5","Edition":"","Line of Business":{"code":"LOB10","label":"Data and AI"}}]

Document Information

Modified date:
25 January 2011