The JBoss 'all' server setup starts up a clustering as a default. But I guess 'all' contains plenty of unnecessary services for a web application based on EJB3, JPA/Hibernate.
What is the minimum setup for JBoss with JBoss Cache clustering?
I'm not sure what the minimum would be in your situation, we don't use the clustering option where I work. However, the only way I could come up with to minimize our setup was to undeploy everything but the services I knew we needed. I then started JBoss and went through the errors in the log to figure out what dependencies were missing, deploy them, and then restart JBoss to get clean logs. I think I had to restart about five times to catch all of the necessary services.
Depends on what you want to cluster (replicate state, that is).
HTTP sessions: jboss/server/node/deploy/jboss-web-cluster.sar/META-INF/jboss-service.xml
EJB 2: .../server/all/deploy/cluster-service.xml
EJB 3: .../deploy/ejb3-clustered-sfsbcache-service.xml and .../deploy/ejb3-entity-cache-service.xml
If you remove something, that is needed by something else, JBoss should complain after the startup finished.