The Data Guard high-availability and disaster recovery option allows for the creation of one or more standby databases. These databases can be brought online in the event that the primary database fails for any reason. The standby database(s) can be accessed in a read-only manner (for example, for reporting) and can be either physical or logical standbys.
For more information on Data Guard, see the Oracle Data Guard document http://www.oracle.com/technetwork/database/features/availability/dataguardoverview-083155.html.