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disc: An optical storage medium for computer information. It consists of a shiny, non-
magnetic metal platter on which information is recorded and read back using
laser technology. See also CD-ROM.
disk: 1) The general term for any circular platter that can store computer information. 2) A
magnetic storage medium, such as a hard disk or diskette. It consists of a
platter or set of platters coated with a magnetic material and enclosed inside a
protective case. See also CD-ROM, hard disk, diskette.
disk cache: A technique that speeds up processing. Each time your application receives
data from a disk, a special program stores the data in a reserved area of
memory (RAM). When the application next requests data, it looks for it first in
the disk cache. Since reading from and writing to memory is quicker than using
a disk drive, this can considerably improve system performance.
disk drive: The device that reads and writes information and programs on a diskette or
hard disk. It rotates the disk at high speed past one or more read/write heads.
diskette: A thin, flexible diskette in a protective jacket that stores magnetically encoded
information. Diskettes can be removed from the computer and come in two
sizes: 5.25-inch and 3.5-inch. The server uses 3.5-inch diskettes.
disk mirroring: A technique in which the contents of a hard disk are duplicated on other
hard disk(s) to protect against data loss. Any changes made to the contents of
the original disk are simultaneously applied to the other disk(s).
disk striping: The spreading of data over multiple hard disks to improve performance. The
technique combines a set of partitions (which must all be the same size)
residing on separate disks into a single volume which the operating system
treats as a logical drive. All the partitions can be accessed at once, greatly
increasing data throughput. Disk striping does not inherently provide fault
tolerance or error checking. It is used in conjunction with other techniques,
such as disk mirroring.
display: A computer screen.
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