IT29334: MQ MFT: RESOURCE MONITOR RETRY BEHAVIOUR DOESN'T WORK

APAR status

• Closed as program error.

Error description

• The Configuring monitor retry behavior for message-to-file
  transfers topic in the MQ V9.1 section of IBM Knowledge Center
  (which can be found at the following URI:
  https://www.ibm.com/support/knowledgecenter/SSFKSJ_9.1.0/com.ibm
  .mq.adm.doc/m2f_mon_retry.htm) contains the following
  information:
  
  "If a message-to-file transfer that is triggered by a resource
  monitor fails and leaves the message group that triggered the
  monitor on the queue, that transfer is resubmitted at subsequent
  poll intervals. The number of times that the transfer is
  resubmitted is limited by the monitorGroupRetryLimit property of
  the monitoring agent."
  
  However, this functionality does not work. If a message-to-file
  transfer fails, it is never resubmitted or retried.
  

Local fix

• Recreate the MFT resource monitor using the -c and -f flags to
  have the failed message-to-file transfers resubmitted.  In
  cases where the user wishes that the resubmitted transfer be
  updated in the MFT transfer log, they must remove the failed
  log entry using the MQ Explorer beforehand.
  

Problem summary

• ****************************************************************
  USERS AFFECTED:
  This issue affects users of IBM MQ Managed File Transfer who
  have agents that perform message-to-file transfers.
  
  
  Platforms affected:
  MultiPlatform
  
  ****************************************************************
  PROBLEM DESCRIPTION:
  IBM MQ V9.1 Managed File Transfer changed the way in which
  message-to-file transfers worked. Rather than destructively
  getting the messages as in previous releases, the source agent
  would browse the messages on the source queue during the
  transfer, and only delete them if the managed transfer was
  successful. This was done to prevent messages from being lost in
  the situations where a managed transfer failed part-way through.
  
  As a result of this change, the resource monitor retry
  functionality no longer worked. This functionality assumed that
  messages would be removed from the source queue during the
  transfer, and would be rolled back in the event that the
  transfer failed. This would cause the backout count of the
  messages to be increased. The resource monitor would then use
  the backout count to determine if a message on the source queue
  needed to be included in a managed transfer. The logic it would
  use is shown below:
  
  - If there is already a transfer with the same ID as that of
  message ID, then:
      - Do not submit a new managed transfer request for the
  message.
  - Else:
      - If the value of the agent property monitorGroupRetryLimit
  is set to -1 then:
          - Submit a new managed transfer for the message.
      - Else:
          - Check the backout count of the message.
          - If the backout count is greater than 1 and less than
  the value of the agent property monitorGroupRetryLimit:
              - Submit a new managed transfer for the message.
          - Else:
              - Leave the message on the queue.
          - End if
      - End if
  - End if
  
  However, as the messages were now browsed by the source agent,
  the backout count would always be zero. This meant that the
  resource monitor would never attempt to retry a failed
  message-to-file transfer.
  

Problem conclusion

• To resolve this issue, MQ Managed File Transfer resource
  monitors have been updated to keep a count of how many times a
  message-to-file transfer has been attempted. Every time a
  message-to-file transfer is started, the monitor updates the
  counter.
  
  The resource monitor will then compare the value of the agent
  property monitorGroupRetryLimit with the value of the counter,
  rather than the backout count of the message, in order to
  determine if a failed message-to-file transfer needs to be
  resubmitted or not.
  
  ---------------------------------------------------------------
  The fix is targeted for delivery in the following PTFs:
  
  Version    Maintenance Level
  v9.1 LTS   9.1.0.7
  v9.2 CD    9.2.1
  
  The latest available MQ 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 MFT V9.1

• Fixed component ID

  5724H7272

Applicable component levels