MQ

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  • 1.  HA for MQ instance but sequencing of messages to be handled

    IBM Champion
    Posted Sat June 25, 2022 05:32 AM
    Hi,

    I have a single QM instance which handles all the messages from our OMS. Since sequencing and order need to be maintained, we didnt design as cluster of QM instances or HA. Because of single instance we are having single point of failure and having down time if there is any issue. Is there a better option for this scenario to handle sequencing of messages and having HA for QM inplace.

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    Thanks,
    Santhosh Ramanathan
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  • 2.  RE: HA for MQ instance but sequencing of messages to be handled

    IBM Champion
    Posted Sat June 25, 2022 05:49 AM
    Hi Santhosh,

    The use of an HA solution based on MQ clusters can indeed lead to a change of sequence in the delivery of messages, even if there are solutions to avoid this, at the level of the configuration of the queues (and by using the GroupId).

    The easiest way to keep the sequence of messages with an HA solution is probably to implement a multi-instance MQ configuration: https://www.ibm.com/docs/en/ibm-mq/9.2?topic=configurations-multi-instance-queue-managers

    On a well-configured environment, the failover time is less than a minute.

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    Luc-Michel Demey
    DEMEY CONSULTING
    lmd@demey-consulting.fr
    #IBMChampion
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  • 3.  RE: HA for MQ instance but sequencing of messages to be handled

    IBM Champion
    Posted Sat June 25, 2022 06:32 AM
    Thank you Luc-Michel . Will try out the multi-instance option. Also is there any best practices and migration steps available for migrating from MQ 8.0.0.8 to MQ 9.2 on a new Linux server. My existing MQ 8 is running on RHEL 7.4 and planning to migrate to MQ 9.2 on new RHEL server.

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    Thanks,
    Santhosh Ramanathan
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  • 4.  RE: HA for MQ instance but sequencing of messages to be handled

    Posted Tue June 28, 2022 05:16 AM

    Hi Santhosh,

    If I'm understanding your scenario correctly, you would be content with either clustering or HA? Since Luc-Michel has already written about clustering, I will focus on HA.

    The official IBM MQ HA solutions (RDQM, Native HA, and the appliance's HA) will assure message sequencing and order for queues on a queue manager, even when they fail-over to another machine in the HA group.
    Note: The messages will need to be persistent messages when placed on the queue, otherwise they will be lost when the queue manager restarts on another machine.
    For your considerations: The IBM MQ Appliance is a 2 node HA solution, whereas "RDQM uses a three node system with quorum to avoid the split-brain situation." and "Native HA uses a three pod system with quorum to avoid the split-brain situation." So, for the appliance: "Be aware that if you lose the network connections between the two appliances, a partitioned situation can arise [...]"

    Sources:



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    Ben Durrans
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  • 5.  RE: HA for MQ instance but sequencing of messages to be handled

    Posted Thu June 30, 2022 07:43 PM
    Hi Santhosh,
    >Since sequencing and order need to be maintained, we didnt design as cluster of QM instances or HA. 
    You would be better off designing the MQ interfaces such that sequencing and order is not required. MQ does not guarantee this anyway, except in specific circumstances. I gasp every time I encounter this type of ill-informed design.
    Best regards,


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    Glenn Baddeley
    Senior Middleware Software Engineer
    Coles Supermarkets Australia Pty Ltd
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