If a node fails during the 2-phase commit protocol, an exception is thrown internally by the comms layer. This is trapped and the transaction is marked for rollback, and the TM sees this and initiates a rollback. If the node does before the 2-pc protocol commences, then the tx does not fail; it just excludes the dead node from the cluster. There is no difference between a shutdown and a node crashing as far as the 2-pc protocol is concerned. If the node dies/is shut down in the middle of the 2-pc protocol, it will cause a rollback on the initiator of the commit. Else, it will be excluded from the cluster before the 2-pc commences. We detect dead nodes using JGroups' failure detection protocols - FD and FD_SOCK. See JGroups docs for details on this. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4006429#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...