Most production Oracle databases have 24-7 availability requirements. Therefore, your only option is online RMAN backups. Your database must be in archivelog mode for online backups. You need to consider carefully to place archive redo logs, how to format them, how often to back them up, and how long to retain them before deletion. These topics are discussed in subsequent sections.
Note If you make offline backups, you must shut down your database with IMMEDIATE, NORMAL, or TRANSACTIONAL and then place it in mount mode. RMAN needs the database in mount mode so that it can read from and write to the control file.