When you execute a log backup the system backs up all redo log entries that have been written since the last log backup from the log area to a data carrier. Once the redo log entries are backed up, the system can overwrite them again in the log area.
To automatically back up log entries, activate automatic log backup.
Database Administration, Backing Up Log Entries
Database Studio, Backing up Log Entries
Database Manager CLI, Backing Up and Restoring Database Instances
Database Administration in CCMS, Scheduling Log Backups