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IZ01794: WEBSPHERE MQ QUEUE MANAGER FAILS TO START WHEN TRANSACTION'S FIRST LSN IS NOT IN ACTIVE LOG AFTER DISK SPACE ISSUE.

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APAR status

  • Closed as program error.

Error description

  • If a transaction fails immediately after reserving a restart
    point in the recovery log then it is possible that the only
    reference to the transaction is in a checkpoint. If the queue
    manager fails with a transaction in this state then it is
    possible that the subsequent restart will fail.
    This is a very small timing window and is very unlikely to
    match subsequent restart problems. Analysing a problem at this
    level is very complex and if a reasonable suspicion of a match
    occurs then L3 should be involved.
    The sequence of probes
    HL008001, AL020000, AT013009, KN002003
    at queue manager restart would indicate a potential duplicate
    of this problem (which should then be verified by L3).
    If the queue manager logs are dumped then the oldest transaction
    will be seen to have a non-null FirstLSN (matching the LSN in
    the HL008001 FDC), but a null LastLSN.
    

Local fix

Problem summary

  • ****************************************************************
    USERS AFFECTED:
    The most likely cause of this problem is that a shortage of
    disk space causes an in-tran MQPUT to fail. IY79906 should also
    be considered in these circumstances, as that resolves a
    checkpoint issue related to disk space issues.
    
    Platforms affected:
     All Distributed (iSeries, all Unix and Windows)
    ****************************************************************
    PROBLEM SUMMARY:
    It is possible for a transaction to be referenced in a
    checkpoint, even though that transaction has never written a
    log record. If the transaction then ends without ever writing a
    log record it is important that the end of the transaction is
    recorded in the log, in case restart recovers the original
    reference and then does not realize the transaction ended.
    The check as to whether to write the end of the transaction log
    record was based only upon whether the transaction had written
    a log record and did not take into account that the transaction
    might have been referenced in a checkpoint without ever
    actually writing a log record (a very rare occurrence).
    

Problem conclusion

  • The decision as to whether the end transaction is recorded in
    the log is now based upon whether the transaction wrote a log
    record, or was referenced in a checkpoint. The number of
    instances where one occurs without the other is so small as to
    be of no consideration from a performance standpoint.
    
    ---------------------------------------------------------------
    The fix is targeted for delivery in the following PTFs:
    
                       v6.0
    Platform           Fix Pack 6.0.2.3
    --------           --------------------
    Windows            U200279
    AIX                U811346
    HP-UX (PA-RISC)    U811630
    HP-UX (Itanium)    U811631
    Solaris (SPARC)    U811632
    Solaris (x86-64)   U811633
    iSeries            SI27288
    Linux (x86)        U811634
    Linux (x86-64)     U811635
    Linux (zSeries)    U811636
    Linux (Power)      U811637
    Linux (s390x)      U811638
    
    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

    IZ01794

  • Reported component name

    WMQ LIN X86 V6

  • Reported component ID

    5724H7204

  • Reported release

    600

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt

  • Submitted date

    2007-07-23

  • Closed date

    2007-07-30

  • Last modified date

    2007-09-04

  • 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

  • R600 PSY

       UP

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Document Information

Modified date:
04 September 2007