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IZ64138: AFTER RESTART FOLLOWING A QUEUE MANAGER CRASH AN FDC IS RAISED WITH PROBE ID AQ123001 COMPONENT AQQLOADMSGHDR.

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APAR status

  • Closed as program error.

Error description

  • There is a timing condition in the WebSphere MQ checkpoint code
    that can lead to the heads of empty message queues not being
    flushed to disk, and resulting in a damaged object after a
    crash recovery.
    
    Probe Id          :- AQ123001
    Component         :- aqqLoadMsgHdr
    Major Errorcode   :- arcE_OBJECT_DAMAGED
    
    MQM Function Stack
    zlaMainThread
    zlaProcessMessage
    zlaProcessMQIRequest
    zlaMQOPEN
    zsqMQOPEN
    kpiMQOPEN
    kqiOpenIt
    kqiOpenQueue
    apiLoadQueue
    aqmLoadQueue
    aqhLoadQueue
    aqhLoadMsgChain
    aqhLoadMsg
    aqqLoadMsgHdr
    xcsFFST
    
    Probe Id          :- AQ060020
    Component         :- aqhLoadMsgChain
    Major Errorcode   :- arcE_OBJECT_DAMAGED
    

Local fix

Problem summary

  • ****************************************************************
    USERS AFFECTED:
    This is a small timing window that could effect any customer
    using persistent messages of differing priorities, who suffers
    from a queue manager crash.
    
    Platforms affected:
    All Distributed (iSeries, all Unix and Windows)
    ****************************************************************
    PROBLEM SUMMARY:
    There is very small timing window where the queue manager does
    not flush the head of an empty message chain to disk during
    checkpoint. If this problem is followed by a queue manager
    crash then this can lead the queue manager to erroneously
    believe there are additional messages on the queue, and can
    result in the queue being detected as damaged.
    This bug has existed in the code since 5.3 GA. The fact that
    the problem has only just been exposed (November 2009) gives an
    indication as to how unlikely the circumstances are in which
    the problem can arise.
    

Problem conclusion

  • The checkpoint code was changed to flush the queue header when
    all of the messages on the queue had been put since the start
    checkpoint log record was written, but one or more of the
    message chains is now empty when it was not empty when the
    queue was last checkpointed.
    
    ---------------------------------------------------------------
    The fix is targeted for delivery in the following PTFs:
    
                       v6.0
    Platform           Fix Pack 6.0.2.9
    --------           --------------------
    Windows            U200313
    AIX                U828012
    HP-UX (PA-RISC)    U827381
    HP-UX (Itanium)    U827383
    Solaris (SPARC)    U827693
    Solaris (x86-64)   U828055
    iSeries            tbc_p600_0_2_9
    Linux (x86)        U827380
    Linux (x86-64)     U827694
    Linux (zSeries)    U827590
    Linux (Power)      U827382
    Linux (s390x)      U827695
    
                       v7.0
    Platform           Fix Pack 7.0.1.2
    --------           --------------------
    Windows            U200316
    AIX                U829807
    HP-UX (PA-RISC)    U829678
    HP-UX (Itanium)    U829681
    Solaris (SPARC)    U829806
    Solaris (x86-64)   U829680
    iSeries            tbc_p700_0_1_2
    Linux (x86)        U829677
    Linux (x86-64)     U829676
    Linux (zSeries)    U829682
    Linux (Power)      U829679
    
    The latest available maintenance can be obtained from
    'WebSphere MQ Recommended Fixes'
    http://www-1.ibm.com/support/docview.wss?rs=171&uid=swg27006037
    
    If the maintenance level is not yet available, information on
    its planned availability can be found in 'WebSphere MQ
    Planned Maintenance Release Dates'
    http://www-1.ibm.com/support/docview.wss?rs=171&uid=swg27006309
    ---------------------------------------------------------------
    

Temporary fix

Comments

APAR Information

  • APAR number

    IZ64138

  • Reported component name

    WMQ LIN X86 V6

  • Reported component ID

    5724H7204

  • Reported release

    601

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2009-10-30

  • Closed date

    2009-11-24

  • Last modified date

    2009-12-17

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

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

Fix information

  • Fixed component name

    WMQ LIN X86 V6

  • Fixed component ID

    5724H7204

Applicable component levels

  • R601 PSY

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Document Information

Modified date:
17 December 2009