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IT29525: MQ Appliance - dltmqm hangs indefinitely on HA QMs

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APAR status

  • Closed as program error.

Error description

  • When running an instance of the dltmqm program simultaneously
    for the same Queue Manager on a pair of HA appliances, the
    program hangs indefinitely.
    The issue also manifests as inconsistent status when multiple HA
    commands are performed concurrently. In this case, HA QMgrs were
    removed from HA group and HA group was deleted.
    HA group was recreated and three QMgrs were added to the HA
    group around the same time.
    However, one of the QMgrs failed to be added to the HA pair.
    On MQ Appliance 1 (mqa1):
    mqa(mqcli)# sethagrp -i  QM1
    Creating high availability configuration on appliance
    AMQ6577E: The command failed because the queue manager already
    exists on the other appliance in the HA Group.
    mqa(mqcli)# status QM1
    QM(QM1)                            Status(Ended unexpectedly)
    Queue manager file system:         92291MB used, 295.3GB
    allocated [31%]
    mqa(mqcli)# sethagrp -e Qm1
    Removing high availability configuration on this appliance.
    Removing high availability configuration on appliance 'mqapp2'.
    AMQ6589W: Failed to remove high availability configuration on
    appliance  'mqa2'.
    The user should issue command 'dltmqm' on remote appliance
    'mqa2' when it becomes available. The sethagrp command
    partially succeeded.
    On MQ Appliance 2 (mqa2):
    Status command shows the QMgr running elsewhere although the
    Qmgr is not running on any of the appliances.
    mqa(mqcli)# status QM1
    QM(QM1)                            Status(Running elsewhere)
    HA role:                           UNKNOWN
    HA status:                         UNKNOWN
    HA control:                        Enabled
    HA preferred location:             None

Local fix

  • N/A

Problem summary

  • ****************************************************************
    Users of HA on the MQ Appliance at version
    Platforms affected:
    Due to a programming error, changes made in MQ regarding
    locking for HA were incomplete. In the scenario where this issue
    is encountered, the locking mechanism was intended to ensure
    that the dltmqm command was only run on one appliance at a time.
    Due to the defective locking logic, the command executed on both
    appliances concurrently, causing the commands to hang.
    This issue was introduced by the changes for IT26873, included
    in the MQ Appliance firmware.

Problem conclusion

  • The code has been updated so that the HA locking function works
    The fix is targeted for delivery in the following PTFs:
    Version    Maintenance Level
    v9.1 CD    9.1.4
    v9.1 LTS
    The latest available maintenance can be obtained from
    'WebSphere MQ Recommended Fixes'
    If the maintenance level is not yet available information on
    its planned availability can be found in 'WebSphere MQ
    Planned Maintenance Release Dates'

Temporary fix


APAR Information

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  • Reported component ID


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  • PE




  • Special Attention

    NoSpecatt / Xsystem

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Fix information

  • Fixed component name


  • Fixed component ID


Applicable component levels

[{"Business Unit":{"code":"BU053","label":"Cloud & Data Platform"},"Product":{"code":"SS5K6E","label":"IBM MQ Appliance"},"Component":"","ARM Category":[],"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"910","Edition":"","Line of Business":{"code":"LOB36","label":"IBM Automation"}}]

Document Information

Modified date:
30 September 2019