Automatic restart recovery after a system failure utilizes the online transaction journal or journals to recover the database to an operational state.
In a full recovery from a backup, all necessary transaction journal files are used. To recover the database to an operational state from the backup, all the archived (or offline) journal files created since the backup was performed are required, as well as the online transaction journal or journals.
It is your responsibility to ensure that transaction journals are backed up. You may not be able to fully recover your database if you do not backup consecutively numbered journal files.
For protection against media failure in production systems, always locate the online and archived transaction journals on a different physical volume to the database files and mirror the transaction journal volume.