"pete.muir(a)jboss.org" wrote : 1) >= 1 SMPC per db (unless you use something like Shards or Metamatrix) | why would you ever need more than one SMPC per db? I can understand having 1 or 2 SMPC's for 2 db's if the db's are on the same server... anonymous wrote : 2) I'm not 100% sure, but I think you need to use XA transactions if you are using multiple datasources AFAIK, XA transactions are necessary only when supporting/using distributed transactions (such as when method A with a required transaction annotation - e.g. REQUIRES or REQUIRESNEW - propagates its transaction to another EntityManager CRUD operation in method B that is called by method A and also requires a transaction). Then a XA datasource is required to enable 2 phase commit protocol where the transaction mgr coordinates commits with the resource mgr's (for the db's). anonymous wrote : 3) If something is @AutoCreate, create=true is redundant, yes. this makes sense. thx. View the original post : http://www.jboss.com/index.html?module=bb&op=viewtopic&p=4126269#... Reply to the post : http://www.jboss.com/index.html?module=bb&op=posting&mode=reply&a...