"nbakizada" wrote : | | I'm having trouble understanding if the 2 nodes in a cluster act as some sort of primary/secondary, or if they're both equal primaries. In the event of a basic failover (one of the 2 appservers goes down), things failover to the other just fine. But what happens if, say, both servers are running, but are somehow unable to connect to each over the network (so each thinks the other is unavailable). What happens to the messages stored in the shared database? | You're referring to network partitioning commonly known as "split brain". In this case both nodes would fail over for each other. This can result in duplicate delivery of messages. Note that exact same issue would arise with JBoss MQ / A.N. other product so is not specific to JBM. It's a general network condition. To mitigate against this you can use IP bonding to add redundancy on the IP level (see JGroups wiki), and code your consumers to be resilient to duplicate messages. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4120747#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...