Oracle RAC is a shared storage system, every database instances write to same datastore, so as long as a transaction is committed by one node, it'll be seen by

Oracle RAC is a shared storage system, every database instances write to same datastore, so as long as a transaction is committed by one node, it'll be seen by other nodes. Of course, the issue with all shared-storage systems is how much it costs to have a reliable and fast shared storage.