OK, just as an update - I've figured out that bundling the war inside another ear - also containing a jar with a new persistence.xml that maps to the war's datasource works as intended. Now bundling the war like this: | webapp1.ear | -> webapp1.war | -> webapp1-persistence.jar | -> persistence.xml | Though, in my original persistence.xml, I point to the jar files containing my entity beans, but in the webapp-ear I cannot do that as it doesn't seem like you can point on jar files inside another ear - so I instead have to point on every single class inside myproject.ear that acts as an entity-bean. This is surely a maintenance-hell when a new entity gets introduced and I need to change all these persistence.xml's in the webapps, rebuild and redeploy. Is there any way to be able to point to those jars even if they are inside another EAR? Some kind of "inherited persistence.xml" would be damn sexy here :( View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4019842#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...