After you have run the high availability installer for WebSphere® Premises Server, you can use these instructions to add more messaging engines.
There are two SIBuses created with the WebSphere Premises Server installation, AMIT and ibmsensorevent.
The high availability cluster configuration is the default configuration created when a cluster of application servers in a cell is created. When the SIBus is created, there is only one active messaging engine on one of the cluster servers, and all service requests to cluster members are routed through this single messaging engine. Therefore, for a cluster of n servers, there is one local message put action for routing the service request on the server with the active messaging engine, and (n-1) remote message put actions for each of the servers with inactive messaging engines.
For workload management, the cluster configuration requires additional configuration from the default cluster installation. The purpose of this configuration is to remove the dependence on the messaging engine remote put calls by explicitly creating an additional messaging engine for each of the servers in the cluster and defining a CoreGroup policy to "assign" the messaging engine to an individual server in the cluster. With n active messaging engines in a cluster of n servers, each service request is processed locally on the server receiving the message rather than getting routed to an active messaging engine.