IBM TS4300 User Manual page 300

Channel command
An instruction that directs a data channel, control unit, or device to run 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.
CM
Cartridge Memory. Within each data cartridge, an embedded electronics and interface module that
can store and retrieve a cartridge's historical usage and other information.
CoD
Capacity on-demand.
Command
A control signal that initiates an action or the start of a sequence of actions.
Compact disc (CD)
A disk, usually 4.75 inches in diameter, from which data is read optically by using 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 that is 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.
Control path drive
ControllerA device that provides the interface between a system and one or more tape drives.Control
path drive A drive that communicates messages from the host computer to the library in which the
drive is installed.
Cookie
A packet of data that is exchanged between the library and a web browser to track configuration.
CP
Circuit protector.
CPF
Control Path Failover.
CRU
Customer Replaceable Unit.
CSA
Canadian Standards Association.
Ctrl
Control.
CU
Control unit.
268 IBM TS4300 Tape Library Machine Type 3555: User's Guide
IBM Confidential