Can I use Oracle RAC in a distributed transaction processing environment?
YES. Best practices is to have all tightly coupled branches of a distributed transaction running on an Oracle RAC database must run on the same instance. Between transactions and between services, transactions can be load balanced across all of the database instances. Prior to Oracle RAC 11g, you must use services to manage DTP environments. By defining the DTP property of a service, the service is guaranteed to run on one instance at a time in an Oracle RAC database. All global distributed transactions performed through the DTP service are ensured to have their tightly-coupled branches running on a single Oracle RAC instance. Oracle RAC 11g provides transparent support for XA global transactions in an Oracle RAC environment and you do not need to use DTP services.