1.6.1. High Availability Singleton Fail-over
The JBoss HA-JMS service (i.e., message queues and topics) only runs on a single node (i.e., the master node) in the cluster at any given time. If that node fails, the cluster simply elects another node to run the JMS service (fail-over). This setup provides redundancy against server failures but does not reduce the work load on the JMS server node.
While you cannot load balance HA-JMS queues (there is only one master node that runs the queues), you can load balance the MDBs that process messages from those queues (see Section 1.6.1.3, “Load Balanced HA-JMS MDBs”).