Cluster message queue

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Within IBM® i high availability environments, you can specify a cluster message queue where you can receive and respond to messages that provide details on failover events in the cluster. This message provides information on all cluster resource groups (CRGs), which are failing over to the same node when the primary node for the CRGs ends or fails.

It is similar to failover message queue, but instead of receiving one message per CRG, you receive only one regarding all the CRGs failing over to the same node. If you have both the cluster message queue and the failover message queue configured, the cluster message queue takes priority. If you prefer failover messages for each CRG within a cluster, you should not configure the cluster message queue. For either message queue, you can use IBM i watch support to monitor these message queues for activity.

The following table describes the action that is performed for each of these message queues:

Table 1. Cluster and failover message queues actions
Cluster message queue defined	Failover message queue defined	Response
No	No	Failover continues with no user action
No	Yes	Message (CPABB01) sent to each CRG's failover message queue on the first backup node
Yes	No	For node-level failovers, one message (CPABB02) is sent to cluster message queue on the first backup node which controls all CRGs failing over to that node. For crg-level failovers, one message (CPABB01) per CRG will be sent to the cluster message queue on the first backup node which controls the individual CRG failing over to that node.
Yes	Yes	CRG failover message queue will be ignored. For node-level failovers, one message (CPABB02) is sent to cluster message queue on the first backup node which controls all CRGs failing over to that node. For crg-level failovers, one message (CPABB01) per CRG is sent to the cluster message queue on the first backup node which controls the individual CRG failing over to that node.

You can define a cluster message queue by providing a name for the queue and a library in which the queue resides. You also can specify the number of minutes to wait for a reply to the failover message. Once this time is exceeded, the specified default failover action will be taken.