Hi vickyk! Thank you for your fast reply. I have read the Documentation and i already had set the <valid-connection-checker-class-name> tag in my oracle-ds.xml File, i use the org.jboss.resource.adapter.jdbc.vendor.OracleValidConnectionChecker Class. Unfortunately it doesn´t work on one machine. So I have copied the jboss to a another machine, there the same jboss is able to reconnect after db restart. So maybe it´s a problem outside jboss (And yes, I know this is a JBoss Froum). May somebody have or had the same issues? View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4105016#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...