title: Error retrieving connections in jboss to multiple databases even though there is no transaction
body: <p>We are in the process of upgrading from JBoss 6 to JBoss 7. The nature of our application has a separate database instance per customer, as well as a core configuration database common to all customers. We often have EJB code which will at least reference the core database plus the individual customer's data in one call, and even some general background processes that go through all customers.</p>
  
  <p>In JBoss 6 this was handled without issue by setting the method with a NOT_SUPPORTED transaction attribute. However, JBoss 7 complains about this with the following error:</p>
  
  <blockquote>
    <p>ARJUNA012140: Adding multiple last resources is disallowed. Trying to
    add
    LastResourceRecord(XAOnePhaseResource(LocalXAResourceImpl@74bec54d[connectionListener=d3ce980
    connectionManager=25b47a05 warned=false currentXid=&lt; formatId=131077,
    gtrid_length=29, bqual_length=36,
    tx_uid=0:ffff0a2c28d1:-5a4c1f9a:504689c9:11, node_name=1,
    branch_uid=0:ffff0a2c28d1:-5a4c1f9a:504689c9:14,
    subordinatenodename=null, eis_name=unknown eis name >])), but already
    have
    LastResourceRecord(XAOnePhaseResource(LocalXAResourceImpl@518d0191[connectionListener=1a05d94a
    connectionManager=135f1cfe warned=false currentXid=&lt; formatId=131077,
    gtrid_length=29, bqual_length=36,
    tx_uid=0:ffff0a2c28d1:-5a4c1f9a:504689c9:11, node_name=1,
    branch_uid=0:ffff0a2c28d1:-5a4c1f9a:504689c9:13,
    subordinatenodename=null, eis_name=unknown eis name >]))</p>
  </blockquote>
  
  <p>How can we work around this problem without wrapping every call to the different databases in a separate EJB call and transaction. Is there a way to actually turn off the JBoss transaction management in an EJB call or something similar?</p>
  
  <p><em>Note: This question was modified after the bounty started based on additional discovery to sharpen the focus on the specific problem and remove other possibilities that were excluded.</em></p>