Product guide
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Appendix C Glossary
Failover:
The process of transferring control of all customer
resources, software applications, disk data, print spooler, etc.,
from the primary server to a surviving server because of a
hardware or software system crash.
Fault Tolerance:
Designed into disk array subsystems to maintain
data integrity and data availability before, during and after a failure.
Fault tolerance implies that any component in a subsystem can
fail and the subsystem will remain operational. In addition to the
disks in any array subsystem, the cabling, controllers, adapters
and power supplies can have redundant capabilities.
FDDI:
Fiber Distributed Data Interface. A 100 Mbps, Megabits per
second, standard LAN architecture. The underlying medium is
fiber-optic cable (though it can be copper cable, in which case it
may be called CDDI) and the topology is a dual-attached, counter-
rotating token ring.
Fiber Optic Cable:
A transmission medium that uses glass or
plastic fibers, rather than copper wire, to transport data or voice
signals. The signal is imposed on the fibers via pulses
(modulation) of light from a laser or a light-emitting diode (LED).
Because of its high bandwidth and lack of susceptibility to
interference, fiber-optic cable is used in long-haul or noisy
applications. FDDI rings are normally constructed in the form of a
"dual ring of trees". A small number of devices, typically
infrastructure devices such as routers and concentrators rather
than host computers, are connected to both rings. Host computers
are then connected as single-attached devices to the routers or
concentrators. The whole dual ring is typically contained within a
computer room.
Firewire:
Officially called IEEE 1394, firewire is a new, very fast
external bus standard that supports data transfer rates of up to
400Mbps (400 million bits per second). A single firewire port can
be used to connect up to 63 external devices. In addition to its
high speed, firewire also supports isochronous data-delivering
data at a guaranteed rate. This makes it ideal for devices that
need to transfer high levels of data in real-time, such as video
devices. Although extremely fast and flexible, firewire is also
much more expensive than a competing external bus standard
called Universal Serial Bus (USB). Like USB, firewire supports
both Plug-and-Play and hot plugging.
Floppy Disk:
A 3.5 inch removable storage medium used for
storing programs and files externally from the computer system.
Format:
A process that prepares a disk to hold data. For hard
disks, there are two formatting processes: low-level and high-
level.
FPM DRAM:
Fast Page Mode Dynamic Random Access
Memory. Most computers in use today use FPM DRAM. If the
data needed is in the same row as the previous data, the
memory controller does not have to repeat the row location; it
only needs to indicate the next column location. Using FPM
memory is like reading a dictionary. As long as the word you
want is on the same "page," it will be easy to scroll down the list
and find the definition; but when you have to flip pages, it takes
a little longer to find what you want.
FULL SCSI:
A SCSI solution that includes BIOS and support
software to provide boot capability for hard disk drives, support
for drives larger than 1 B, and full compatibility with removable
media products (hard drives, optical drives, tape drives, and
Floptical drives).
FRU:
Field Replacement Unit.
Gateway:
A device that can interconnect networks with
different, incompatible communications protocols. The gateway
performs a layer-7 protocol-conversion to translate one set of
protocols to another. A gateway operates at Open Systems
Interconnection (OSI) layers up through the Session Layer.