Active-Passive High Availability Setup
In this setup, you maintain a duplicate of the active database and update it regularly. You copy the log backups of the original database to the standby database server and import them into the standby database. When the original database fails, you can quickly resume operations with the standby database after importing the most recent redo log entries.
Standby databases are updated at regular intervals. The updates are performed synchronously or asynchronously. In a synchronous setup, log writes are considered successful only if logs have been written to log files on the active database and if the active database has received acknowledgment from the standby database that the logs have also been written to log files.
As an alternative to the above setup, you can also use a passive standby database server that shares the disks for data storage with the active database server. This setup protects you against server failure, but not against storage failure.
