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fiber optic cable. The medium by which light is
transmitted through fibers or thin rods of glass or some
other transparent material of high refractive index.
fiber optics. A branch of optics dealing with the
transmission of light through fibers or thin rods of glass
or some other transparent material of high refractive
index.
Fibre Channel. A 100-MB-per-second, full-duplex,
serial communications technology that is capable of
interconnecting Ultrium Tape Drives and servers which
are separated by as much as 11 kilometers (7 miles).
Fibre Channel technology combines features of the
input/output (I/O) and networking interfaces.
Fibre Channel address. For a tape drive that uses a
Fibre Channel interface, an identifier (such as an AL_PA
or Loop ID) that enables other device ports to
communicate with that drive. A Fibre Channel drive has
a 3-byte address. The switch assigns the upper 2 bytes
of the address. If no switch is attached, the 2 bytes
equal 0. The lower byte assignment (which is the
AL_PA) varies, depending on whether hard or soft
addressing is used.
Fibre Channel cable. The cable that connects a Fibre
Channel tape drive to another device. The conductive
element within the cable is constructed of either copper
wires or optical fibers. Generally, copper wires are used
for short distances (up to 30 meters or 98 feet); optical
fibers are used for longer distances. Fiber-optic cabling
is referred to by mode or the frequencies of light waves
that are carried by a particular cable type. Multimode
fiber cables are generally used for distances up to 500
meters (1640 feet) and with short-wave (780
nanometer) laser light. Single-mode fiber cables are
used for distances greater than 500 m (1640 feet) and
with long-wave (1300 nanometer) laser light.
Fibre Channel wrap test. A diagnostic that causes the
Ultrium Tape Drive to perform a check of the Fibre
Channel circuitry from and to the drive’s Fibre Channel
connector or the fiber cable.
field microcode replacement tape. A tape cartridge
that contains new or revised firmware (microcode) for
the Ultrium Tape Drive.
file. A named set of records that are stored or
processed as a unit.
filemark. Located on the magnetic tape within a tape
cartridge, a recorded element that typically marks the
organizational boundaries in a serial file structure (such
as directory boundaries) and that is requested to be
written or read by the server.
firmware. Proprietary code that is usually delivered as
part of an operating system. Firmware is more efficient
than software that is loaded from an alterable medium,
and is more adaptable to change than pure hardware
circuitry. An example of firmware is the Basic
Input/Output System (BIOS) in read-only memory
(ROM) on a PC motherboard.
FMR tape. See field microcode replacement tape.
foot. A unit of length comprising 12 inches.
G
GB. See gigabyte.
gigabyte (GB). 1 000 000 000 bytes.
ground. An object that makes an electrical connection
with the earth.
H
hard addressing. Pertaining to the Fibre Channel
drive (Model T200F), a method that identifies the drive’s
LID and, consequently, its AL_PA (the AL_PA enables
the drive to communicate with other devices).
hardware. The physical equipment or devices that
form a computer.
head. See drive head.
Head Resistance Measurements test. Part of the
Test Head diagnostic, a procedure that determines
whether the tape drive’s head works correctly. The test
measures the head’s ability to withstand cracks and
other defects.
host. The controlling or highest-level system in a data
communication configuration. Synonymous with server.
hot-pluggable. Pertaining to the Ultrium Tape Drive,
the ability to remove the drive from an enclosure while
the enclosure is powered-on.
hub. A communications device to which nodes on a
multi-point bus or loop are physically connected. Hubs
are commonly used in Fibre Channel networks to
improve the manageability of physical cables. They
maintain the logical loop topology of the network of
which they are a part, while creating a “hub and spoke”
physical star layout. Unlike switches, hubs do not
aggregate bandwidth. They typically support the addition
or removal of nodes from the bus while it is operating.
I
IBM Ultrium Internal Tape Drive. See Ultrium Internal
Tape Drive.
ID. Identifier.
in. See inch.
inch. A unit of length equal to 1/36 yard or 25.4 mm.
Glossary 95
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