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IT26372: Managed File Transfer agent event logs do not rotate

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APAR status

  • Closed as program error.

Error description

  • The agent.properties file for a MFT agent contans an optional
    property "outputLogFiles" that controls how many agent event
    logs are generated.
    
    For example:
      outputLogFiles=5
    
    This should mean 5 event logs, called:
    
    - output0.log
    - output1.log
    - output2.log
    - output3.log
    - output4.log
    
     are generated and roll over as needed. However, once an agent
    fills up the final log file, the event logs are not rotated.
    Instead, the current output0.log file is deleted and a new one
    created.
    

Local fix

Problem summary

  • ****************************************************************
    USERS AFFECTED:
    This issue affects users of IBM MQ Managed File Transfer.
    
    
    Platforms affected:
    MultiPlatform
    
    ****************************************************************
    PROBLEM DESCRIPTION:
    Every Managed File Transfer agent has its own event log, which
    it uses to store informational messages as well as details of
    any errors that the agent has encountered. The number of files
    used to hold the event log, as well as the size of each file, is
    controlled by the agent properties:
    
    - outputLogFiles
    - outputLogSize
    
    The current event log file is called output0.log file, and
    historical event log files are called output<number>.log, where
    <number> is a value greater than 0.
    
    Details of the two properties mentioned above can be found in
    the:
    
      The agent.properties file
    
    topic in the IBM MQ sections of IBM Knowledge Center. The URI
    for this topic in the IBM MQ V8, V9.0.x and V9.1.x sections of
    IBM Knowledge Center are shown below:
    
    IBM MQ V8.0
    http://www-01.ibm.com/support/knowledgecenter/SSFKSJ_8.0.0/com.i
    bm.wmqfte.doc/properties.htm
    
    IBM MQ V9.0.x
    https://www.ibm.com/support/knowledgecenter/en/SSFKSJ_9.0.0/com.
    ibm.wmqfte.doc/properties.html
    
    IBM MQ V9.1.x
    https://www.ibm.com/support/knowledgecenter/en/SSFKSJ_9.1.0/com.
    ibm.mq.ref.con.doc/properties.htm
    
    
    When an agent started up, it began writing to the current event
    log (output0.log). When this file reached its maximum size, as
    specified by the agent property outputLogSize, the agent would
    attempt to rename the event log files using the following logic:
    
    - Get the name of the oldest historical log file.
    - Rename the second oldest log file so that it has the name of
    the oldest historical log file.
    - Rename the third oldest log file, so that it has the name of
    the second oldest log file.
    - And so on.
    - After all of the historical log files have been renamed,
    rename the current log file (output0.log) to be output1.log.
    
    The agent then started to write to the new output0.log file.
    
    However, if the maximum number of historical log files (as
    specified by the agent property outputLogFiles) had been
    reached, the agent did not delete the oldest historical log file
    before performing the rename operations. This meant that:
    
    - Once the maximum number of historical log files had been
    created,
    - And the current event log file had reached its maximum size
    
    the rename operations would fail, as the target files already
    existed. As a result, the historical log files were not rotated.
    
    For example, suppose that an agent has been configured with the
    following agent properties:
    
    outputLogFiles=2
    outputLogSize=1
    
    When the agent started up, it created a new output0.log file,
    and started writing to it. When the file reached 1MB in size,
    the agent:
    
    - Renamed the output0.log file to output1.log.
    - Created a new output0.log file.
    
    After running for a period of time, the new output0.log file
    reached 1MB. When this happened, the following behaviour
    occurred:
    
    - The agent attempted to rename the existing output0.log file to
    output1.log. However, this rename operation failed as the
    output1.log file already existed.
    - The agent then created a new output0.log file, overwriting the
    original one, and started writing to it.
    
    As a result, the information in the previous output0.log file
    was lost.
    

Problem conclusion

  • IBM MQ Managed File Transfer has been updated so that:
    
    - If the maximum number of historical log files have been
    created (as specified by the agent property outputLogFiles).
    - And the current event log has reached its maximum size (as
    defined by the agent property outputLogSize).
    
    then agents will delete the oldest historical log file before
    renaming the other log files. This ensures that the rename
    operations work as expected, and the event logs to be rotated
    correctly.
    
    ---------------------------------------------------------------
    The fix is targeted for delivery in the following PTFs:
    
    Version    Maintenance Level
    v8.0       8.0.0.11
    v9.0 LTS   9.0.0.6
    v9.1 CD    9.1.1
    v9.1 LTS   9.1.0.2
    
    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 number

    IT26372

  • Reported component name

    IBM MQ MFT V8.0

  • Reported component ID

    5724H7252

  • Reported release

    800

  • Status

    CLOSED PER

  • PE

    NoPE

  • HIPER

    NoHIPER

  • Special Attention

    NoSpecatt / Xsystem

  • Submitted date

    2018-09-20

  • Closed date

    2018-10-02

  • Last modified date

    2018-10-02

  • 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 V8.0

  • Fixed component ID

    5724H7252

Applicable component levels

[{"Business Unit":{"code":"BU050","label":"BU NOT IDENTIFIED"},"Product":{"code":"SSYHRD","label":"IBM MQ"},"Component":"","ARM Category":[],"Platform":[{"code":"PF025","label":"Platform Independent"}],"Version":"8.0","Edition":""}]

Document Information

Modified date:
02 October 2018