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  • 1.  IBMi - MQ channels Sequence numbers ... Where are these numbers stored ?

    Posted Mon March 03, 2025 09:54 AM

    Hello,

    For my information ... 

    Within MQ environments on IBMi, how can I verify the current Sequence number within SDR & RCV channels ?

    And any idea where (dir/subdir/stmf ?) is this information stored on IBMi. 

    I'm facing regularly issues with channel startup processing failing due to an incorrect seq number. And it looks like a NLS issue (different users/different countries/ different Job CCSIDs) is causing this issue.  But for recovery automation, I was looking for info where I could find this seq number, as I'm not always in charge of the SDR channels, where a reset (to 1) can solve the issue quickly.

    Kind regards,

    Thanks,

    Jos



    ------------------------------
    Jos (Jozef) Thijs
    Kyndryl Belgium
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  • 2.  RE: IBMi - MQ channels Sequence numbers ... Where are these numbers stored ?

    Posted Mon March 03, 2025 05:08 PM

    Hi Jos,

    Make use of the DISPLAY CHSTATUS commands.

    If you use DISPLAY CHSTATUS(chl-name) SAVED ALL you will see the channel sequence number each end last hardened, and where they will try to start from again when next restarting. Look at the CURSEQNO and LSTSEQNO fields.

    I'm not sure exactly what you mean by an "NLS issue" with respect to sequence numbers. Is it likely that you have the same partner queue manager being run on different machines and picking up different state, and thus sending an unexpected sequence number?

    If your DISPLAY CHSTATUS SAVED output shows several different partners then that would also be enlightening.

    Cheers,
    Morag



    ------------------------------
    Morag Hughson
    MQ Technical Education Specialist
    MQGem Software Limited
    Website: https://www.mqgem.com
    ------------------------------

    Original Message


  • 3.  RE: IBMi - MQ channels Sequence numbers ... Where are these numbers stored ?

    Posted Tue March 04, 2025 05:39 AM

    Hi Jos,

    Morags suggestion to use the tooling provided by MQ to query the sequence numbers in the SAVED channel status should help you to understand channel sequence number mismatches. Whilst the different users/countries involved in the channels that are affected may appear to be significant, a channel sequence number mismatch is typically caused by a loss of state at either end of a channel, that could be through;

    • Administrative deletion and redefinition of a channel
    • Backup/restore of older data files
    • A DR failover
    • A 'cold-start' following abnormal end of a queue manager (skipping 'redo' in queue manager startup)
    • Incorrect use of RESET CHANNEL

    The difference in sequence numbers is often a good indication of what happened, for example a sequence mismatch between 1 and a much larger number might indicate a deletion or RESET CHANNEL, whilst a difference between two values both greater than 1 might indicate a restored backup, a DR failover or a cold-start.

    If you know that you are encountering a channel sequence number mismatch because of a DR failover and want to avoid needing to issue a RESET CHANNEL, you can opt to use IgnoreSeqNumMismatch Channel message sequence numbering

    Ibm remove preview
    Channel message sequence numbering
    The channel uses sequence numbers to check that messages are delivered in the same order as they are taken from the transmission queue.
    View this on Ibm >

     

    If you are unable to identify one of these possible causes, you should be raising a support ticket with IBM.



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    Jonathan Rumsey
    Senior Software Engineer
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    Original Message


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