The unit also has robotic arms to retrieve the

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Unformatted text preview: tape drives for processing. The tape is automatically returned to the library at the end of the job. A large tape library can accommodate up to several hundred high capacity magnetic tapes bringing the storage capacity of the storage unit to several terabytes (1 terabyte is equal to one trillion bytes). Automated tape libraries are typically used for data archiving and as an on-line data backup device for automated backup. They are mainly found in large computer centres. CD-ROM Jukebox The principle of operation of a CD-ROM jukebox is very similar to that of an automated tape library except for the fact that it uses a set of CD-ROMs instead of magnetic tapes as the storage media. That is, a CD-ROM jukebox is a set of CD-ROM disks with a controller mounted in a single unit. The unit has one or more CD-ROM drives to read data from the CD-ROM disks in the jukebox. In case of units having multiple CD-ROM drives, it is possible to read data from multiple CD-ROM disks simultaneously resulting in faster data transfer rates. Multiple drives also lead to improved reliability of the storage unit because if one of the drives fails, the unit can continue to function with other drives at a slower speed. The unit also has robotic arms to retrieve the appropriate CD-ROM and mount it on one of the CD-ROM drives for processing. The CD-ROM is automatically returned to the appropriate slot at the end of the job. A large CD-ROM jukebox can accommodate up to several hundred CD-ROM disks bringing the storage capacity of the storage unit to several terabytes. CD-ROM jukeboxes are typically used for archiving read-only data that needs to be accessed on-line but where access time is not very critical. For example, on-line museums, on-line digital libraries and on-line encyclopedia are a few systems that may make use of this mass storage device in an effective manner. OTHER RELATED CONCEPTS Few other concepts related to secondary storage of computer systems are briefly described below. Drive Interface Standards Secondary storage devices need a controll...
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This document was uploaded on 04/07/2014.

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