Quantum Scalar 218FC User Manual page 117

Fibre Channel (FC)
Fibre Channel - Arbitrated
Loop (FC-AL)
Fibre Channel Protocol for
SCSI (FCP)
Frame
Gigabit Link Module (GLM)
Hardware Path
Host Bus Adapter
HSM
Initiator
LCD
Logically, Fibre Channel is a bi-directional, full-duplex, point-to-point,
serial data channel structured for high performance capability. Physically,
the Fibre Channel is an interconnection of multiple communication ports,
called N_Ports, interconnected by a switching network, called a fabric, a
point-to-point link, or an arbitrated loop. Fibre Channel is a generalized
transport mechanism that has no protocol of its own or native input/output
command set, but can transport any existing Upper Level Protocols
(ULPs) such as SCSI and IPI. Fibre Channel operates at speeds of 100
Mbytes/sec (full speed), 50 Mbytes/sec (half speed), 25 Mbytes/sec
(quarter speed) or 12.5 Mbytes/sec (eighth speed), over distances of up to
100 m over copper media or up to 10 km over optical links.
One of three existing Fibre Channel topologies, in which 2 to 126 devices
are interconnected serially in a single loop circuit. The arbitrated loop
topology supports all classes of service and guarantees in order delivery
of frames when the source and destination are on the same loop.
FCP defines a Fibre Channel mapping layer (FC-4) that uses FC-PH
services to transmit SCSI command, data, and status information between
a SCSI initiator and a SCSI target. Using FCP enables transmission and
receipt of SCSI commands, data and status, across the Fibre Channel
using the standard Fibre Channel frame and sequence formats.
The smallest, indivisible unit of information transfer used by FC-2.
Frames are used for transferring data associated with a sequence. Frame
size depends on the hardware implementation and is independent of the
ULP or the application software. Frames begin with a 4-byte Start of
Frame (SOF), end with a 4-byte End of Frame (EOF), include a 24-byte
frame header and a 4-byte Cyclic Redundancy Checker (CRC), and can
carry a variable data payload from 0 to 2112 bytes, the first 64 of which
can be used for optional headers.
A physical component that manages the functions of the FC-0 layer,
which is the physical characteristics of the media and interface, including
drivers, transceivers, connectors, and cables. Also referred to as a Physical
Link Module (PLM).
See FC-SCSI Hardware Path ID.
See FC adapter.
Hierarchical Storage Management – a system where different types of
storage medium are used based on cost and time efficiency. For example,
for fastest access, data is usually stored on a local drive. If you have a
very large file that is needed occasionally, you may store it on a tape in
the Scalar 218FC, or on an optical drive. In an HSM system, the data
source should be transparent to the user.
A SCSI device (usually a host system) that requests an operation to be
performed by another SCSI device known as the target (e.g., a SCSI disk
or tape drive).
Liquid Crystal Display, a commonly used alphanumeric display that
responds to specified input voltages and signals
Glossary 107