Logger events

Logger events are notifications that a queue manager has started writing to a new log extent or, on IBM i, a journal receiver. Logger event messages are not available with IBM MQ for z/OS .

The event data contains the following information:

  • The name of the current log extent.
  • The name of the earliest log extent needed for restart recovery.
  • The name of the earliest log extent needed for media recovery.
  • The directory in which the log extents are located.
  • The name of the earliest log extent for which archive notification is required.

    From IBM MQ Version 9.1.0, a logger event is generated for archive log management, that is, when ARCHLOG changes, and the ARCHLOG value will be included the logger event message.

    See DISPLAY QMSTATUS for more information on all these parameters.

    We can use the CURRLOG and ARCHLOG values to determine what should be archived. Whenever CURRLOG changes, files with numbers less than CURRLOG can be sent for archive and, once archiving has been completed for the extent, we should call SET LOG to notify the queue manager.

    ARCHLOG is the oldest extent that needs archiving. When you have archived that extent and called SET LOG to notify the queue manager that it has been archived, the queue manager moves ARCHLOG to the next extent in sequence. The queue manager schedules extents that are older than ARCHLOG, to be deleted or reused.

    Once SET LOG has been called for this extent a new event is issued, as ARCHLOG will have changed, and we need to know what needs to be archived after the new event.

    If for some reason your archiving process fails, and a big build up of notifications happens, your administrator can manually issue the command RESET QMGR TYPE(ARCHLOG). This notifies the queue manager that it can reuse or delete all extents older than, and including, the extent you specified.

Every logger event message that is generated is placed on the logger event queue, SYSTEM.ADMIN.LOGGER.EVENT.

  • Logger event generation
    Use this page to view the situations that cause logger events to be generated and to understand the circumstances in which logger events are not generated
  • Logger event usage
    Use this page to view how we can use logger events to determine the log extents that are no longer required for queue manager restart, or media recovery.
  • Sample C program to monitor the logger event queue
    Use this page to view a sample C program that monitors the logger event queue for new event messages, reads those messages, and puts the contents of the message to stdout.

Parent topic: Event monitoring


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