IBM Support

IJ02451: MQ may incorrectly reset the log counter to zero

Subscribe to this APAR

By subscribing, you receive periodic emails alerting you to the status of the APAR, along with a link to the fix after it becomes available. You can track this item individually or track all items by product.

Notify me when this APAR changes.

Notify me when an APAR for this component changes.

APAR status

  • Closed as program error.

Error description

  • MQ could potentially incorrectly reset the the MQ transaction
    log LSN to zero resulting in a log sequence number outside the
    expected range.
    
    In this state, the next time the queue manager was ended, it
    could not be started.
    
    An FFST with the following notable characteristics is generated:
    
    | Probe Id          :- HL008001
    | Component         :- hlgSetLogRestartLsn
    | Program Name      :- amqzmuc0
    | Major Errorcode   :- xecF_E_INVALID_PARAMETER_VALUE
    
    MQM Function Stack
    zmuThreadMain
    zmuCheckpointTask
    alsCheckPointLoop
    aocPerformCheckpoint
    atmSetOldestTranLSN
    almSetOldestTranLSN
    hlgSetLogRestartLsn
    xcsFFST
    
    Within the FFST data, the dbcb structure also contains the
    lowtranlsn of 0:
        lowtranlsn:                <0:0:0:0> 0X0000000000000000
    

Local fix

Problem summary

  • ****************************************************************
    USERS AFFECTED:
    IBM MQ installations on modern processors utilising instruction
    re-ordering optimisations.
    
    
    Platforms affected:
    MultiPlatform
    
    ****************************************************************
    PROBLEM DESCRIPTION:
    Instruction re-ordering on modern processors could lead to
    internal state flags being set in an unexpected order and
    resulting in an incorrect code path to be followed and
    corruption of the LSN values.
    

Problem conclusion

  • The MQ code had been resolved to ensure the code path execution
    is synchronised with the processor instruction caches to avoid
    the flags being set incorrectly.
    
    ---------------------------------------------------------------
    The fix is targeted for delivery in the following PTFs:
    
    Version    Maintenance Level
    v7.5       7.5.0.9
    v8.0       8.0.0.9
    v9.0 CD    9.0.5
    v9.0 LTS   9.0.0.3
    
    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

    IJ02451

  • Reported component name

    WMQ AIX V7

  • Reported component ID

    5724H7221

  • Reported release

    710

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    YesHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2017-12-06

  • Closed date

    2018-01-22

  • Last modified date

    2018-02-12

  • 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 AIX V7

  • Fixed component ID

    5724H7221

Applicable component levels



Document information

More support for: WebSphere MQ
APAR / Maintenance

Software version: 710

Reference #: IJ02451

Modified date: 12 February 2018


Translate this page: