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LI73100: INTERNAL RESOURCE CONTENTION DURING PARALLEL ONLINE BACKUP MAY LEAD TO LESS THAN OPTIMAL THROUGHPUT

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APAR status

  • Closed as program error.

Error description

  • When performing an online parallel backup, the I/O activity will
    be done by the prefetcher processes.
    In the current algorithm, these can be seen as competing for the
    same resource when examining repeated stack traces of these
    processes during a backup process.
    
    A typical stack exposing this contention would show :
    
       getConflictComplex__17SQLO_SLATCH_CAS64FCUl + 0x244
       getConflict__17SQLO_SLATCH_CAS64FCUl + 0xE0
    
    @28@3@sqloltch_track__FCP10sqlo_latchCUlCPCcT2C14SQLO_LT_VALUES
    - 0x58
       sqlbLatchPoolRange__FP12SQLB_GLOBALSUsUiT3PiT5ib + 0x334
       sqlbDMSDirectRead__FP17SQLB_DIRECT_IO_CB + 0x14
       sqlbDirectRead__FP17SQLB_DIRECT_IO_CB - 0x6C
       sqlbServiceDirectReadRequest__FP11SQLB_pfMisc + 0x6BC
       sqlbPFPrefetcherEntryPoint__FPcUi + 0x444
    
    This apar reduces the resource latching needed and should hence
    improve throughput during the online backup.
    
    The impact of this problem depends on the speed of the backup
    media
    ( this is the bottleneck in most cases ). The speed of the
    offline backup with the same parameters is a reasonable measure
    of the fastest throughput that can be achieved, but online will
    always carry more overhead.
    

Local fix

  • n/a
    

Problem summary

  • Problem summary : suboptimal online backup performance due to
    internal latching contention
    Users Affected : all ( parallel ) online backup users
    Problem conclusion : this apar improves online backup
    performance
    

Problem conclusion

  • This problem was first fixed in v9.1 fixpak 7.
    

Temporary fix

Comments

APAR Information

  • APAR number

    LI73100

  • Reported component name

    DB2 UDE ESE LIN

  • Reported component ID

    5765F4104

  • Reported release

    910

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2008-01-30

  • Closed date

    2009-04-28

  • Last modified date

    2009-04-28

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

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

    LI73105

Fix information

  • Fixed component name

    DB2 UDE ESE LIN

  • Fixed component ID

    5765F4104

Applicable component levels

  • R910 PSN

       UP

  • R950 PSN

       UP

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Document Information

Modified date:
28 April 2009