We perform two different types of system backups: a daily backup of small files only, and a weekly backup of all files on selected disks. In both cases, the backups are simply to other disks in the department; we do not have any tape backups, so there is an inherent risk in our backup systems, as any event that were to wipe out files on multiple disks in the department could wipe out both original and backup versions! If possible, all users are advised to backup critical files themselves on some external backup medium.