In the event of a disaster you should (if possible) archive the current on-line logs of the primary database, then transfer and apply these logs to the standby database before activating the standby database. The standby database will then be current to the same point in time and transactional history as the primary database before the failure. If you cannot archive your current on-line logs, then you must activate the standby database without recovering the transactions from the unarchived logs of the primary database.
To activate a standby database, perform the following procedures:
ALTER DATABASE MOUNT STANDBY DATABASE EXCLUSIVE
ALTER DATABASE ACTIVATE STANDBY DATABASE
At the completion of the activate command, the database is no longer considered a standby database, but is now a production database. For this reason it is recommended that the database be backed-up immediately.
Activating the standby database resets the on-line log files and modifies the control file. After activation, the standby database can not be returned to standby recovery mode.