Oracle Corporation offers an optional Hot Standby software
    solution that you can use to implement a standby database for
    mission-critical and disaster recovery functions.

    A standby database is a second running database that is created
    from and transactionally consistent with the primary or master
    database. Data modifications that are made to the master database
    are made simultaneously to the secondary database. The secondary
    database is sometimes referred to as a hot standby database
    because it is available immediately to pick up application
    processing if the primary database system fails.

    The Hot Standby software prevents your Oracle Rdb database or
    Oracle CODASYL DBMS database from becoming a single point of
    failure by replicating the master database to a standby database.
    The Hot Standby software automatically performs coordinated
    database synchronization and verification with high performance
    and minimal impact on the master system resources.