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IC76792: BAD PAGE HEADER ENCOUNTERED BY PREFETCHER DURING ONLINE BACKUP ON LINUX PLATFORM. BACKUP IMAGE MAY BE CORRUPTED.

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You can track all active APARs for this component.

APAR status

  • Closed as program error.

Error description

  • This problem exists only in V9.7 Fix pack 3 and Fix pack 4 on
    the Linux platform.
    
    
    Conditions through which the Bad Page Header is encountered:
    
    1)  Linux operating system
    2)  DB2 V9.7 using either Fix pack 3 or Fix pack 4
    3)  Tablespaces with multiple containers
    4)  Online backup
    5)  Significant user activity which drives prefetching during
    online backup
    
    
    There are 2 possible consequences:
    
    1)  Incorrect pages are silently written to the online backup.
    Any restore from this backup image will result in data
    corruption.
    2)  Bad Page Header messages encountered by prefetchers during
    the online backup.
    
    
    2011-06-01-21.04.29.871752-240 I495774E3614        LEVEL: Severe
    PID    : 11263                TID  : 47129540159808PROC :
    db2sysc
    INSTANCE: db2inst1        NODE : 000
    EDUID  : 134                  EDUNAME: db2pfchr (SAMPLE)
    FUNCTION: DB2 UDB, buffer pool services, sqlb_verify_page,
    probe:13
    MESSAGE : ZRC=0x87020036=-2029912010=SQLB_BADHDR "Bad Page
    Header"
              DIA8547C An error occurred in a database page header.
    DATA #1 : String, 64 bytes
    Error encountered trying to read a page - information follows :
    DATA #2 : String, 23 bytes
    Page verification error
    DATA #3 : Page ID, PD_TYPE_SQLB_PAGE_ID, 4 bytes
    9678
    DATA #4 : Object descriptor, PD_TYPE_SQLB_OBJECT_DESC, 88 bytes
        Obj: {pool:4;obj:4;type:1} Parent={4;4}
      lifeLSN:      0000000010F75884
      tid:          0 0  0
      extentAnchor:                8490
      initEmpPages:                  0
      poolPage0:                      0
      poolflags:                  3122
      objectState:                  27
      lastSMP:                        0
      pageSize:                  16384
      extentSize:                    2
      bufferPoolID:                  2
      partialHash:            17039364
      bufferPool:    0x00002adc27f347c0
      pdef:          0x00002adc2de8aec0
    DATA #5 : Bitmask, 4 bytes
    0x00000002
    DATA #6 : Page header, PD_TYPE_SQLB_PAGE_HEAD, 48 bytes
    pageHead: {tbspSeed:4;obj:4;type:0} PPNum:2770 OPNum:2762
      begoff:                      48
      datlen:                  16336
      pagebinx:                    0
      revnum:                    1280
      pagelsn:    000000000238ED4C  flag:                        2
      future32:                    0
      cbits1to31:            1c02807
      cbits32to63:                  0
    
    CALLSTCK:
      [0] 0x00002ADBBF2955A2 pdLog + 0x398
      [1] 0x00002ADBBFF73186
    _Z25sqlbLogReadAttemptFailurejP16SQLB_OBJECT_DESCjP9SQLB_PAGEibm
    jPcP12SQLB_GLOBALS
    + 0x1BE
      [2] 0x00002ADBC1A59352
    _Z16sqlb_verify_pageP9SQLB_PAGEP16SQLB_OBJECT_DESCjjP12SQLB_GLOB
    ALSPm
    + 0x376
      [3] 0x00002ADBBF2CDFF8
    _Z25sqlbReadAndReleaseBuffersP16SQLB_OBJECT_DESCjmmmP11SQLB_pfMi
    sc
    + 0x984
      [4] 0x00002ADBBF2CC538
    _Z16sqlbProcessRangeP16SQLB_OBJECT_DESCjjP11SQLB_pfMisc + 0x140
      [5] 0x00002ADBBF2CB7B7
    _Z26sqlbPFPrefetcherEntryPointP16sqbPrefetcherEdu + 0x3C9
      [6] 0x00002ADBBF2CB3AD _ZN16sqbPrefetcherEdu6RunEDUEv + 0x2F
      [7] 0x00002ADBBFA9732C _ZN9sqzEDUObj9EDUDriverEv + 0xA6
      [8] 0x00002ADBBFA97283 _Z10sqlzRunEDUPcj + 0x9
      [9] 0x00002ADBBF80B3D2 sqloEDUEntry + 0x2F4
    
    
    The db2diag.log entries in the above example show that DB2
    requested page 9678 from tablespace 4, but received page 2770
    from tablespace 4. In order to verify the occurrence of the bad
    page header issue, the received page must be in the same
    tablespace as the requested page.
    

Local fix

  • For the following command:
    
    db2set DB2BPVARS=<file>
    
    Replace <file> with a fully qualified file name, such
    as /home/db2inst1/bpvars.cfg
    
    Place the following line in the stated file:
    
    NOREADVBCKUP=1
    
    Restart DB2 to propagate changes.
    

Problem summary

  • ****************************************************************
    * USERS AFFECTED:                                              *
    * linux                                                        *
    ****************************************************************
    * PROBLEM DESCRIPTION:                                         *
    * see error description                                        *
    ****************************************************************
    * RECOMMENDATION:                                              *
    * upgrade to v97 FixPack 5.                                    *
    ****************************************************************
    

Problem conclusion

  • see local fix
    

Temporary fix

Comments

APAR Information

  • APAR number

    IC76792

  • Reported component name

    DB2 FOR LUW

  • Reported component ID

    DB2FORLUW

  • Reported release

    970

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    YesHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2011-06-03

  • Closed date

    2011-10-31

  • Last modified date

    2012-06-21

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

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

    IC83352

Fix information

  • Fixed component name

    DB2 FOR LUW

  • Fixed component ID

    DB2FORLUW

Applicable component levels

  • R970 PSN UP

       FIX



Document information

More support for: DB2 for Linux, UNIX and Windows

Software version: 9.7

Reference #: IC76792

Modified date: 21 June 2012


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