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IT20368: SQLB_BADHDR ERROR DURING SQLB_VERIFY_PAGE CAUSING FODC DUMPS ANDDB MARKED BAD.

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APAR status

  • Closed as program error.

Error description

  • Some partial writes/reads may occur during rebalance/reduce max
    or lower high water mark operations causing SQLB_BADHDR errors,
    FODC dumps and bringing down db2.
    
    With this defect fix, a new registry variable is being
    introduced so that when set, it will verify extents in the
    following manner to prevent any future bad pages and/or dump
    detailed diagnostic data into db2diag.log and into a binary dump
    for further root cause analysis:
    
    -New registry variable DB2_EM_PAGE_VERIFICATION (db2set
    DB2_EM_PAGE_VERIFICATION=TRUE)
       -Extent verification during rebalance operations
          -Verifies that one full extent is read successfully, it
    does not verify data consistency of extent's pages
          -If extent read was not successful, retry read 2 more
    times
          -Verbose logging that dumps diagnostic data on failed
    reads, and states if re-reads were successful
          -If read fails both re-reads, release latches and wait for
    1 minute then retry extent move operation (retry forever)
       -Extent verification during reclaim storage (i.e. LOWER HIGH
    WATER MARK, REDUCE MAX)
          -Verifies that each page of extent has correct checksum
    pending the page header is not corrupted
          -If bad page identified, re-read extent up to 2 more times
          -If all re-reads fail, stop extent movement and return
    error
          -Verbose logging that dumps diagnostic data on failed
    reads, and states if re-reads were successful
    
    With this defect fix, there is also an update to an existing DB2
    registry:
    
    -Updated registry variable DB2_BCKP_PAGE_VERIFICATION (db2set
    DB2_BCKP_PAGE_VERIFICATION=TRUE)
       -Extent verification during offline/online backup
          -Same page verification as extent verification during
    reclaim storage
          -Updated retry on failure to re-read extent up to 2 more
    times
    

Local fix

Problem summary

  • ****************************************************************
    * USERS AFFECTED:                                              *
    * ALL                                                          *
    ****************************************************************
    * PROBLEM DESCRIPTION:                                         *
    * See Error Description                                        *
    ****************************************************************
    * RECOMMENDATION:                                              *
    * Upgrade to Db2 11.1 Mod 3 Fix Pack 3 or higher               *
    ****************************************************************
    

Problem conclusion

  • First fixed in Db2 11.1 Mod 3 Fix Pack 3
    

Temporary fix

Comments

APAR Information

  • APAR number

    IT20368

  • Reported component name

    DB2 FOR LUW

  • Reported component ID

    DB2FORLUW

  • Reported release

    B10

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2017-04-26

  • Closed date

    2018-03-19

  • Last modified date

    2018-03-19

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

    IT20332

  • 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

  • RB10 PSN

       UP

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Document Information

Modified date:
19 March 2018