Glossary 255
Draft Document for Review April 7, 2004 6:15 pm 6947glos.fm
ESA/390. See Enterprise Systems Architecture/390.
ESCD console. The ESCON Director display and
keyboard device used to perform operator and service
tasks at the ESCD.
ESCD. Enterprise Systems Connection (ESCON)
Director.
ESCON channel. A channel having an Enterprise
Systems Connection channel-to-control-unit I/O
interface that uses optical cables as a transmission
medium. May operate in CBY, CNC, CTC or CVC
mode. Contrast with parallel channel.
ESCON Director. An I/O interface switch that provides
the interconnection capability of multiple ESCON
interfaces (or FICON FCV (9032-5) in a distributed-star
topology.
ESCON Multiple Image Facility (EMIF). In the
ESA/390 architecture, a function that allows LPARs to
share an ESCON channel path (and other channel
types) by providing each LPAR with its own
channel-subsystem image.
ESCON. See Enterprise System Connection.
FCS. See fibre channel standard.
FCTC. FICON Channel-to-Channel
fiber optic cable. See optical cable.
fiber optics. The branch of optical technology
concerned with the transmission of radiant power
through fibers made of transparent materials such as
glass, fused silica, and plastic.
Note: Telecommunication applications of fiber optics
use optical fibers. Either a single discrete fiber or a
non-spatially aligned fiber bundle can be used for each
information channel. Such fibers are often called
optical fibers to differentiate them from fibers used in
non-communication applications.
fiber. See optical fiber.
fibre channel standard. An ANSI standard for a
computer peripheral interface. The I/O interface
defines a protocol for communication over a serial
interface that configures attached units to a
communication fabric. The protocol has four layers.
The lower of the four layers defines the physical media
and interface, the upper of the four layers defines one
or more logical protocols (for example, FCP for SCSI
command protocols and FC-SB-2 for FICON for
ESA/390). Refer to ANSI X3.230.1999x.
FICON channel. A channel having a fibre-channel
channel-to-control-unit I/O interface that uses optical
cables as a transmission medium. The FICON channel
may operate in(1) FC mode (FICON native mode -
FC-SB-2/3), (2) FCV mode (FICON conversion mode to
a IBM 9032-5), (3) FCP mode (FICON channel
operating in “open mode”, which is FC-FCP).
FICON. (1) An ESA/390 and z/Architecture computer
peripheral interface. The I/O interface uses ESA/390
and z/Architecture logical protocols over a FICON
serial interface that configures attached units to a
FICON communication fabric. (2) An FC4 adopted
standard that defines an effective mechanism for the
export of the SBCON command protocol via fibre
channels.
field replaceable unit (FRU). An assembly that is
replaced in its entirety when any one of its required
components fails.
FRU. See field replaceable unit.
Giga bit. Usually used to refer to a data rate, the
number of Giga bits being transferred in one second.
Giga byte. Usually used to refer to an amount of
storage space or size. One Giga-byte is 109, or
1,073,741,824 bytes.
half duplex. In data communication, pertaining to
transmission in only one direction at a time. Contrast
with duplex.
hard disk drive. (1) A storage media within a storage
server used to maintain information that the storage
server requires. (2) A mass storage medium for
computers that is typically available as a fixed disk or a
removable cartridge.
HDA. Head and disk assembly.
HDD. See hard disk drive.
head and disk assembly. The portion of an HDD
associated with the medium and the read/write head.
I/O configuration. The collection of channel paths,
control units, and I/O devices that attaches to the
processor. This may also include channel switches (for
example, an ESCON Director).
I/O. See input/output.
ID. See identifier.
Identifier. A unique name or address that identifies
things such as programs, devices or systems.