This illustration shows a Data Guard configuration consisting of a primary site and a standby site. On the left-hand side of the figure, there is a terminal running an application that is sending read/write transactions to the primary site. The primary site (in San Francisco) includes the following main components: the primary database, online redo logs archiving to the local archived redo logs and over the Oracle Net services to the archived redo logs on the standby site (in Boston). On the Boston standby site, the figure shows the archived redo logs being applied to the standby database. On the right-hand side of the figure, there is a terminal running an application that is performing read-only transactions on the standby database.