IT29525: MQ Appliance 9.1.0.2 - dltmqm hangs indefinitely on HA QMs

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
  'mqa1'.
  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 AFFECTED:
  Users of HA on the MQ Appliance at version 9.1.0.2
  
  
  Platforms affected:
  MultiPlatform
  
  ****************************************************************
  PROBLEM DESCRIPTION:
  Due to a programming error, changes made in MQ 9.1.0.2 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 9.1.0.2 Appliance firmware.
  

Problem conclusion

• The code has been updated so that the HA locking function works
  correctly.
  
  ---------------------------------------------------------------
  The fix is targeted for delivery in the following PTFs:
  
  Version    Maintenance Level
  v9.1 CD    9.1.4
  v9.1 LTS   9.1.0.3
  
  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 is sysrouted FROM one or more of the following:

• APAR is sysrouted TO one or more of the following:

Fix information

• Fixed component name

  IBM MQ APPL M20

• Fixed component ID

  5725Z0900

Applicable component levels