The difference in musical jukebox and optical jukebox is that optical disk library, the platters are optical and contain objects such as data, audio, video and images. Instead of a turn able, an optical disk has one or more optical drives.

Another difference is optical disk library uses a very high speed and accurate servo-controlled electromechanical robotically elevator mechanism for moving the optical platters from a drive and return it to its slot on the stack after the disk has finished playing. Optical disk libraries range from desktop jukeboxes with on 5" drive and a 10 -slot optical disk stack for up to 10 GB of storage to large libraries using as many as four12" drives with an 80 -slot optical disk stack for up to terabytes of storage.

A jukebox may contain drives of different types, including WORM, re-writable or multi-function. Jukebox can contain one or more drives. The drive is daisy chained on a SCSI bus with their own SCSI IDS. The robotics device also behaves as a SCSI device with its own SCSI ID, thereby allowing programmatic control of the device. The size of jukebox varies from small desktop versions.

Way of using

Jukebox based optical disk libraries can be networked so that multiple users can access the information. Optical disk libraries serve as near-line archive for audio and video serves for audio and video objects stored as part of old but nit purged office mail.

Performance

The best case performance is achieved when the required information is in an optical disk which is already mounted in a drive. The worst case performance is when the required information is on the platter and which is not mounted in a drive and all drives have other mounted disk volumes.

The optical disk library logic can be unmounted and returned to its slot. The required disk volume is then fetched by the robotics and inserted into the drive and spun to its rated speed (20-25 s). The disk access and transferred time are so so small compared to the disk fetch and insertion time and mechanical latencies for the robotics that are almost inconsequential in this case.

Applications

Optical disks provide the most effective media i.e. almost on-line. The following examples illustrate the types of multimedia applications that are good candidates for hierarchical storage.

• Police records with fingerprints and mug shots require multimedia applications. Video interviews of witnesses and criminals, and their associated documents, can be stored permanently on WORM disk libraries to provide a vast resource database.

• Insurance companies can photograph or video clips of vehicles and accident scene and store them on optical disk for use during processing claims.

• City and country Government use optical storage for maintaining near-line electronic database of paper files on properties and constituents for tax records, deed recording and so on.