Without getting into to many details here is a quck explanation and a fix: Being on the same network you are attempting to Join the cluster (weather you like it or not). You can clearly see that two JGroups stacks are talking and shunning mambers since they belong to a different grous. Start your JBoss as follows: run -c <conf_name> -g ELECTRA_PARTITION -u 230.1.2.10 run -c <conf_name> -g HYPERION_PARTITION -u 230.1.2.11 Opotion -g will create a unique name for a cluster partition, so you won't have a conflict such as DefaultPartition. Option -u will override a default Multicast address. With that, your servers will not even see each other. On the oposute side if you do want two of them join the cluster thenmake suer that values of -g and -u are the same on bothe machines View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=3985000#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...