On the surface that makes sense, but I do want the security (ie the transactionality) that using Oracle offers for my application. In other words, the consumers of the message also update Oracle data, so I want the 2PC transactionality of (ACK of JMS message == updates were performed). If I don't use a transactional DS for persistence, I can't guarantee that. Plus, even if I used the Hypersonic (or filesystem) persistence, there still is persistence involved. In other words, when you use JMS, the messages are going to be persisted somewhere across server reboots. Which brings me back to my original question... Can you override this default behavior, that is can you have the persistence manager clear its message cache upon startup? View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4047591#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...