Switching active cluster-sender channels to another set of cluster-transmission queues

This task gives you three options for switching active cluster-sender channels. One option is to let the queue manager make the switch automatically, which does not affect running applications. The other options are to stop and start channels manually, or to restart the queue manager.

Before starting

Change the cluster transmission queue configuration. We can change the DEFCLXQ queue manager attribute, or add or modify the CLCHNAME attribute of transmission queues.

If you reduce the number of messages the switching process has to transfer to the new transmission queue, switching completes more quickly. Read How the process to switch cluster-sender channel to a different transmission queue works for the reasons for trying to empty the transmission queue before proceeding any further.

About this task

Use the steps in the task as a basis for working out your own plan for making cluster-transmission queue configuration changes.

Procedure

1. Optional: Record the current channel status Make a record of the status of current and saved channels that are serving cluster transmission queues. The following commands display the status associated with system cluster transmission queues. Add your own commands to display the status associated with cluster-transmission queues that you have defined. Use a convention, such as XMITQ. ChannelName, to name cluster transmission queues that you define to make it easy to display the channel status for those transmission queues.

   DISPLAY CHSTATUS(*) WHERE(XMITQ LK 'SYSTEM.CLUSTER.TRANSMIT.*')
   DISPLAY CHSTATUS(*) SAVED WHERE(XMITQ LK 'SYSTEM.CLUSTER.TRANSMIT.*')
   

2. Switch transmission queues.
   • Do nothing. The queue manager switches cluster-sender channels when they restart after being stopped or inactive.

     Choose this option if you have no rules or concerns about altering a queue manager configuration. Running applications are not affected by the changes.

   • Restart the queue manager. All cluster-sender channels are stopped and restarted automatically on demand.

     Choose this option to initiate all the changes immediately. Running applications are interrupted by the queue manager as it shuts down and restarts.

   • Stop individual cluster-sender channels and restart them.

     Choose this option to change a few channels immediately. Running applications experience a short delay in message transfer between your stopping and starting the message channel again. The cluster-sender channel remains running, except during the time you stopped it. During the switch process messages are delivered to the old transmission queue, transferred to the new transmission queue by the switching process, and forwarded from the new transmission queue by the cluster-sender channel.

3. Optional: Monitor the channels as they switch Display the channel status and the transmission queue depth during the switch. The following example display the status for system cluster transmission queues.

   DISPLAY CHSTATUS(*) WHERE(XMITQ LK 'SYSTEM.CLUSTER.TRANSMIT.*')
   DISPLAY CHSTATUS(*) SAVED WHERE(XMITQ LK 'SYSTEM.CLUSTER.TRANSMIT.*')
   DISPLAY QUEUE('SYSTEM.CLUSTER.TRANSMIT.*') CURDEPTH
   

4. Optional: Monitor the messages AMQ7341 The transmission queue for channel ChannelName switched from queue QueueName to QueueName that are written to the queue manager error log.

Parent topic: Clustering: Switching cluster transmission queues