Have been looking a bit more at this and seems that, according to the jboss-ds_1_5.dtd , the local-tx-datasource type of datasource takes a url-delimiter. And when I deploy with | <datasources> | <local-tx-datasource> | <jndi-name>jdbc/BOB-DS</jndi-name> | <connection-url>jdbc:oracle:thin:@db1:1521:db1|jdbc:oracle:thin:@db2:1521:db2</connection-url> | <url-delimiter>|</url-delimiter> | | <driver-class>oracle.jdbc.driver.OracleDriver</driver-class> | <user-name>USERNAME</user-name> | <password>PASSWORD</password> | | <min-pool-size>2</min-pool-size> | <max-pool-size>20</max-pool-size> | | <check-valid-connection-sql>select 1 from dual</check-valid-connection-sql> | <valid-connection-checker-class-name>org.jboss.resource.adapter.jdbc.vendor.OracleValidConnectionChecker</valid-connection-checker-class-name> | <exception-sorter-class-name>org.jboss.resource.adapter.jdbc.vendor.OracleExceptionSorter</exception-sorter-class-name> | </local-tx-datasource> | </datasources> | | All seems fine. Though I have NOT tested the failover capability. View the original post : http://www.jboss.org/index.html?module=bb&op=viewtopic&p=4216545#... Reply to the post : http://www.jboss.org/index.html?module=bb&op=posting&mode=reply&a...