When continuous availability (24 hours-a-day processing) is required, which one of the following
provides a good alternative to tape backups?

A.
Disk mirroring

B.
Backup to jukebox

C.
Optical disk backup

D.
Daily archiving

Explanation:
Hierarchical Storage Management (HSM). HSM provides continuous on-line backup
by using optical or tape ‘jukeboxes,’ similar to WORMs. It appears as an infinite disk to the system,
and can be configured to provide the closest version of an available real-time backup. This is
commonly employed in very large data retrieval systems.” Pg. 71 Krutz: The CISSP Prep Guide.