PH47266: ABN=5C6-00E20045,M=CSQGFRCV,LOC=CSQILPLM.CSQIUOWA+00000662

Obtain the fix for this APAR.

APAR status

• Closed as program error.

Error description

• During a QMGR restart it fails with the abn 5c6-00E20045
  because of a partially deleted shared queue. When a task then
  tries to open the queue the error causes it to loop. The
  looping task is part of a display queue command running on DB2
  server. Checkpoint processing then runs and issues a query to
  DB2, and this unluckily picks the same DB2 server task and is
  queued behind the looping  task. That meant checkpoints were no
  longer being written, but the tests continued doing lots of
  persistent/recoverable work.
  The QMGR was then cancelled, leaving a huge backlog of
  outstanding recovery processing since the last successful
  checkpoint. On the next startup the volume of this recovery
  processing resulted in the various memory problems.
  

Local fix

Problem summary

• ****************************************************************
  * USERS AFFECTED: All users of IBM MQ for z/OS Version 9       *
  *                 Release 2 Modification 0 and                 *
  *                 Release 3 Modification 0.                    *
  ****************************************************************
  * PROBLEM DESCRIPTION: When MQ checkpointing has stalled a     *
  *                      Queue Manager could get into an         *
  *                      unrecoverable situation after the logs  *
  *                      containing the most recent checkpoint   *
  *                      have been reused.                       *
  ****************************************************************
  If logging activity continues after MQ checkpoint processing has
  stalled for long enough the log containing the most recent
  checkpoint could be reused. This has the potential to leave the
  Queue Manager in an unrecoverable situation as there would be no
  checkpoint to rebuild the Queue Manager from.
  

Problem conclusion

• A new message CSQJ169E has been added to indicate when the last
  checkpoint is no longer contained on any of the active logs.
  When this scenario is detected this new message will be output
  during active log switch processing to indicate to the user that
  checkpoint processing may have stalled. Action may need to be
  taken to ensure that a new checkpoint is taken to prevent the
  Queue Manager from proceeding into an unrecoverable situation.
  
  The IBM Documentation is updated as follows:
  
  Both the V930 & V920 doc pages below will have new entries for
  message CSQJ169E:
  IBM MQ
   -Reference
    -Messages and reason codes
     -IBM MQ for z/OS messages,completion, and reason codes
      -Messages for IBM MQ for z/OS
       -Recovery log manager messages (CSQJ...)
  
  CSQJ169E
      LAST CHECKPOINT NOT FOUND IN ACTIVE LOG COPY & WITH
  STARTRBA=&, CHECKPOINT RBA=&.
  
      Explanation
  
  During active log switch processing the last checkpoint was not
  found on any active logs. This could leave the Queue Manager in
  an unrecoverable position if there are insufficient archive logs
  available to find the required recovery point during restart
  processing. This may be an indication that checkpoint processing
  may have stalled or is not completing in a timely manner and
  should be investigated.
  
      System action
  
  Log switch processing will continue.
  
      System programmer response
  
  You may be able to re-establish checkpointing by stopping and
  restarting the Queue Manager. If checkpointing is stalled, the
  STOP QMGR command may not be able to shut down the Queue Manager
  normally. If this happens, then the Queue Manager may need to be
  cancelled. Before doing so, ensure that the logs from the
  restart RBA onwards are available. The restart RBA can be found
  using the DISPLAY USAGE command.
  
  If it appears that checkpointing has stalled, then take a dump
  of the Queue Manager Address Space and contact your IBM support
  center for assistance to help understand why checkpointing may
  have stalled.
  
  If checkpointing does not appear to have stalled, then an
  alternative reason for this situation might be that the Queue
  Managers active logs are too small for the current workload and
  checkpoint processing is not completing during the scope of one
  active logs lifespan.
  

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:

  UI93668 UI93669 UI93670 UI93671 UI93672 UI93673 UI93674 UI93675
  UI93676 UI93677 UI93678 UI93679

Modules/Macros

• CSQFJDIC CSQFJDIE CSQFJDIF CSQFJDIK CSQFJDIU CSQFLTXC CSQFLTXE
  CSQFLTXF CSQFLTXK CSQFLTXU CSQFMTXC CSQFMTXE CSQFMTXF CSQFMTXK
  CSQFMTXU CSQJW307
  

Fix information

• Fixed component name

  IBM MQ Z/OS V9

• Fixed component ID

  5655MQ900

Applicable component levels

• R200 PSY UI93674

     UP23/10/10 P F310

• R201 PSY UI93675

     UP23/10/10 P F310

• R202 PSY UI93676

     UP23/10/10 P F310

• R203 PSY UI93677

     UP23/10/10 P F310

• R204 PSY UI93678

     UP23/10/10 P F310

• R205 PSY UI93679

     UP23/10/10 P F310

• R300 PSY UI93668

     UP23/10/10 P F310

• R301 PSY UI93669

     UP23/10/10 P F310

• R302 PSY UI93670

     UP23/10/10 P F310

• R303 PSY UI93671

     UP23/10/10 P F310

• R304 PSY UI93672

     UP23/10/10 P F310

• R305 PSY UI93673

     UP23/10/10 P F310

Fix is available

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