IBM L5U, Maintenance Information

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D-2
TS3400 Tape Library Maintenance Information
boot . To load the first piece of software that starts the
library.
browser . A client program that initiates requests to a
Web server and displays the information that the server
returns.
buffer . A routine or storage used to compensate for a
difference in rate of flow of data or time of occurrence of
events, when transferring data from one device to
another.
bus . A facility for transferring data between several
devices located between two end points, only one device
being able to transmit at a given moment.
byte . A string consisting of a certain number of bits
(usually 8) that are treated as a unit and represent a
character. A fundamental data unit.
C
CA certification . In cryptography, a certificate from a
Certificate Authority (CA).
capacity . The amount of data that can be contained on
storage media and expressed in bytes of data.
cartridge manual rewind tool . A device that can be
fitted into the reel of a cartridge and used to rewind tape
into or out of the cartridge.
cartridge memory (CM) . Within each data cartridge,
an embedded electronics and interface module that can
store and retrieve a cartridge’s historical usage and other
information.
cartridge storage slot . Individual slot located within a
magazine that is used to house tape cartridges.
caution (notice) . A word to call attention to possible
personal harm to people. Contrast with attention and
danger .
CE . Customer engineer; field engineer; service
representative.
centimeter (cm) . One one-hundredth of a meter (0.01
m). Approximately 0.39 inch.
channel command . An instruction that directs a data
channel, control unit, or device to perform an operation
or set of operations.
char . Character.
CHK . Check.
cleaning cartridge . A tape cartridge that is used to
clean the heads of a tape drive. Contrast with data
cartridge .
command . A control signal that initiates an action or
the start of a sequence of actions.
compact disc (CD) . A disc, usually 4.75 inches in
diameter, from which data is read optically by means of
a laser.
compression . The process of eliminating gaps, empty
fields, redundancies, and unnecessary data to shorten
the length of records or blocks.
concurrent . Refers to diagnostic procedures that can be
run on one control unit while the rest of the subsystem
remains available for customer applications.
contingent connection . A connection between a
channel path and a drive caused when a unit check
occurs during an I/O operation.
controller . A device that provides the interface
between a system and one or more tape drives.
CP . Circuit protector.
ctrl . Control.
CU . Control unit.
D
danger (notice) . A word to call attention to possible
lethal harm to people. Contrast with attention and
caution .
data . Any representations such as characters or analog
quantities to which meaning is or might be assigned.
data buffer . The storage buffer in the control unit. This
buffer is used to increase the data transfer rate between
the control unit and the channel.
data cartridge . A tape cartridge dedicated to storing
data. Contrast with cleaning cartridge .
data check . A synchronous or asynchronous indication
of a condition caused by invalid data or incorrect
positioning of data.
dc . Direct current.
degauss . To make a magnetic tape nonmagnetic by
means of electrical coils carrying currents that neutralize
the magnetism of the tape.
degausser . A device that makes magnetic tape
nonmagnetic.
degradation . A decrease in quality of output or
throughput or an increase in machine error rate.
degraded . Decreased in quality of output or
throughput or increased machine error rate.