User`s guide

372 Implementing an Open IBM SAN
Class-1 A class of service providing dedicated
connection between two ports with confirmed
delivery or notification of non-deliverability.
Class-2 A class of service providing a frame
switching service between two ports with
confirmed delivery or notification of
non-deliverability.
Class-3 A class of service providing frame
switching datagram service between two ports or
a multicast service between a multicast originator
and one or more multicast recipients.
Class-4 A class of service providing a fractional
bandwidth virtual circuit between two ports with
confirmed delivery or notification of
non-deliverability.
Class-6 A class of service providing a multicast
connection between a multicast originator and
one or more multicast recipients with confirmed
delivery or notification of non-deliverability.
Client A software program used to contact and
obtain data from a server software program on
another computer -- often across a great
distance. Each client program is designed to work
specifically with one or more kinds of server
programs and each server requires a specific
kind of client program.
Client/Server The relationship between
machines in a communications network. The
client is the requesting machine, the server the
supplying machine. Also used to describe the
information management relationship between
software components in a processing system.
Cluster A type of parallel or distributed system
that consists of a collection of interconnected
whole computers and is used as a single, unified
computing resource.
Coaxial Cable A transmission media (cable)
used for high speed transmission. It is called
coaxial because it includes one physical channel
that carries the signal surrounded (after a layer of
insulation) by another concentric physical
channel, both of which run along the same axis.
The inner channel carries the signal and the outer
channel serves as a ground.
Controller A component that attaches to the
system topology through a channel semantic
protocol that includes some form of
request/response identification.
CRC Cyclic Redundancy Check - An
error-correcting code used in Fibre Channel.
DASD Direct Access Storage Device - any
on-line storage device: a disc, drive or CD-ROM.
DAT Digital Audio Tape - A tape media
technology designed for very high quality audio
recording and data backup. DAT cartridges look
like audio cassettes and are often used in
mechanical auto-loaders. typically, a DAT
cartridge provides 2GB of storage. But new DAT
systems have much larger capacities.
Data Sharing A SAN solution in which files on a
storage device are shared between multiple
hosts.
Datagram Refers to the Class 3 Fibre Channel
Service that allows data to be sent rapidly to
multiple devices attached to the fabric, with no
confirmation of delivery.
dB Decibel - a ratio measurement distinguishing
the percentage of signal attenuation between the
input and output power. Attenuation (loss) is
expressed as dB/km
Disk Mirroring A fault-tolerant technique that
writes data simultaneously to two hard disks
using the same hard disk controller.
Disk Pooling A SAN solution in which disk
storage resources are pooled across multiple
hosts rather than be dedicated to a specific host.
DLT Digital Linear Tape - A magnetic tape
technology originally developed by Digital
Equipment Corporation (DEC) and now sold by
Quantum. DLT cartridges provide storage
capacities from 10 to 35GB.
E_Port Expansion Port - a port on a switch used
to link multiple switches together into a Fibre
Channel switch fabric.
ECL Emitter Coupled Logic - The type of
transmitterusedtodrivecoppermediasuchas
Twinax, Shielded Twisted Pair, or Coax.