Switching from primary controller to backup controller

You can plan to switch processing from a primary controller to its backup (for example, for maintenance reasons) or command the backup controller to take over from the primary controller for an unexpected event, such as a system crash or controller abend.

Note: After issuing a BKTAKEOVER command, the processing of critical paths is not automatically performed. You must replan the current plan.

Switching controller as a planned event

To switch from the primary controller to the backup controller as a planned event:
  1. From the primary controller, send the JS1 and JS2 files to the backup controller by using the following procedures after replacing EQQ with your controller subsystem name:
    • EQQSJS1
    • EQQSJS2
    Note: This transfer is particularly important if you use the automatic recovery function.
  2. Stop the primary controller.
    The controller stops when all events have been sent to the backup controller. On the backup controller, the following message is stored in EQQMLOG:
    EQQBT17W CONNECTION RESET BY PEER
  3. On the backup controller, enter the modify command /F procname,BKTAKEOVER
    The available partners establish a connection with the backup controller and synchronize with it.
    Note: The BKTAKEOVER command is run only if the primary controller is completely stopped.

Switching controller for an unplanned event

If the primary controller ends processing unexpectedly, to switch to the backup controller, complete the following steps:
  1. On the backup controller, enter the modify command /F procname,BKTAKEOVER

    The backup controller applies all the events in queue and switches from normal backup mode to active mode. The connection with the partners is established and a synchronization process occurs.

  2. Check the jobs that were in started status on the primary controller when the connection failed, and manually correct the status on the backup controller.