This image shows an Oracle Data Guard configuration consisting of a Primary Site and a Standby site. The Primary Site has three applications with data flow to Primary DB Host1 and Primary DB Host2 on the primary database. The Standby Site has three applications with data flow to Standby DB Host1 and Standby DB Host2 on the standby database.

From the primary database, data flows from Transmit Redo to Redo Stream to Apply Redo on the standby database.