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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.
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.
- Spring '14