What happens when a cluster queue manager fails

When a cluster queue manager fails, some undelivered messages are sent to other queue managers in the cluster. Messages that are in-flight wait until the queue manager is restarted. Use a high-availability mechanism to restart a queue manager automatically.

Problem

If a message-batch is sent to a particular queue manager and that queue manager becomes unavailable, what happens at the sending queue manager?

Explanation

Except for non-persistent messages on an NPMSPEED(FAST) channel, the undelivered batch of messages is backed out to the cluster transmission queue on the sending queue manager. On an NPMSPEED(FAST) channel, non-persistent messages are not batched, and one might be lost.

• Indoubt messages, and messages that are bound to the unavailable queue manager, wait until the queue manager becomes available again.
• Other messages are delivered to alternative queue managers selected by the workload management routine.

Solution

The unavailable cluster queue manager can be restarted automatically, either by being configured as a multi-instance queue manager, or by a platform-specific high availability mechanism.