A printed circuit assembly which transmits user data (I/Os) between the host system's internal bus and the external Fibre Channel link and vice versa. Also called an I/O adapter, host adapter, or FC adapter.


The logical location of a peripheral device, node, or any other unit or component in a network. The formatted number specifying a specific network location.

See also [ SCSI Addressing ]

Arbitrated Loop
See [ Fibre Channel Arbitrated Loop (FC-AL) ]

The second byte of the N_Port Identifier.


The difference (loss) between transmitted and received power, due to the transmission loss through equipment lines or other communications devices.


The range of frequencies that can pass over a given circuit. Generally, the greater the bandwidth, the more information that can be sent through the circuit in a given amount of time.


The encoded bit rate per second. A measure of transmission speed.


A means of transferring data between modules and adapters or between an adapter and SCSI devices. For a SCSI bus definition,

See also [ SCSI ]

Cascaded FC-AL Hubs

One FC-AL hub connected to another FC-AL hub to increase arbitrated loop distances. Cascaded hubs allow distances up to 10 Kilometers between hubs, or 500 meters between a hub and a device.

Class of Service

The types of services provided by the Fibre Channel topology and used by the communicating port.


The most significant byte in the N_Port Identifier for the FC device. It is not used in the FC-SCSI hardware path ID. It is required to be the same for all SCSI targets logically connected to an FC adapter.


A Fibre Channel term that describes a crosspoint switched network, which is one of three existing Fibre Channel topologies. A fabric consists of one or more fabric elements, which are switches responsible for frame routing. The fabric structure is transparent to the devices connected to it and relieves them of the responsibility for station management.

See [ Fibre Channel Arbitrated Loop (FC-AL) ]
FC-AL device

A device that uses Fibre Channel Arbitrated Loop, which consists of one or more NL_Ports.

FC-AL Port

The port on the FC-AL hub that provides connection between the FC-AL adapter and the FC-AL link.

FC-SCSI Hardware Path ID

A list of values showing the physical hardware path of the host to the target device.


 Bus_Converter/Adapter_Address.Protocol_Type.Area.  Port.Bus.Target.LUN 

Example: 8/

See [ Fibre Optic Cable ]
Fiber Optics

A technology that uses light as an information carrier. Fiber optic cables are a direct replacement for conventional coaxial cable and wire pairs. The glass-based transmission facility occupies less physical volume for an equivalent transmission capacity, and the fibers are immune to electrical interference.


A generic Fibre Channel term used to cover all transmission media specified in the Fibre Channel Physical Layer standard (FC-PH), including optical fibre, copper twisted pair, and copper coaxial cable.

Fibre Optic Cable

An optical fibre cable made from thin strands of dielectric material, such as glass, through which data in the form of light pulses is transmitted by laser or LED. Fibre optic cable is used for high-speed transmission over medium to long distances.

Fibre Channel

Logically, Fibre Channel is a bidirectional, full-duplex , point-to-point, serial data channel structured for high performance capability. Physically, Fibre Channel interconnects devices, such as host systems and servers, FC hubs and disk arrays, through ports, called N_Ports, in one of three topologies: a point-to-point link, an arbitrated loop, or a crosspoint switched network, which is called a fabric. FC can interconnect two devices in a point-to-point topology, from two to 126 devices in an arbitrated loop.

FC is a generalized transport mechanism that has no protocol or native I/O command set, but can transport any existing protocol, such as SCSI, in FC frames . FC is capable of operating at speeds of 100 MB/s (full speed), 50 MB/s (half speed), 25 MB/s (quarter speed), or 12.5 MB/s ( eighth speed), over distances of up to 100 m over copper media or up to 10 km over optical links. The disk array operates at full speed.

Fibre Channel Arbitrated Loop (FC-AL)

One of three existing Fibre Channel topologies, in which two to 126 ports are interconnected serially in a single loop circuit. Access the FC-AL is controlled by an arbitration scheme. The FC-AL topology supports all classes of service and guarantees in-order delivery of FC frames when the originator and responder are on the same FC-AL. The disk array's default topology is arbitrated loop.

Fibre Channel Arbitrated Loop Hub

A full-duplex, 1.063 Gigabit per second intelligent hub used in a FC-AL topology to increase the loop's reliability, the number of loop connections, and the distances between the host system(s) and disk array(s). A maximum of ten devices can be connected to each FC-AL hub.

Fibre Channel Protocol for SCSI (FCP)

FCP defines a high-level Fibre Channel mapping layer (FC-4) that uses lower-level Fibre Channel (FC-PH) services to transmit SCSI command, data, and status information between a SCSI initiator and a SCSI target across the FC link using FC frame and sequence formats.


A collection of bits that contain both control information and data; the basic unit of transmission on a network. Control information is carried in the frame with the data to provide for such functions as addressing, sequencing, flow control, and error control to the respective protocol levels. It can be of fixed or variable length.

The smallest, indivisible unit of application-data transfer used by Fibre Channel. Frame size depends on the hardware implementation and is independent of 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 Check (CRC), and can carry a variable data payload from 0 to 2112 bytes, the first 64 of which can be used for optional headers.

Gigabit Link Module (GLM)

A physical component that manages the functions of the FC-0 layer, which are the physical characteristics of the media and interface, including driver, transceivers, connectors, and cables. Also referred to as a Physical Link Module (PLM).


In the context of peripheral devices, a processor that runs an operating system using a disk array for data storage and retrieval.


A repeater used to connect several nodes in a network. A hub is a concentration point for data and repeats data from one node to all other connected nodes.


Light emitting diode.

Light Emitting Diode

A small light on a device that is often used to provide status information.


In Fibre Channel, it is two unidirectional fibres transmitting in opposite directions and their associated transmitters and receivers that serve as the communication media between nodes in a topology. Comparable to a bus in the SCSI protocol.

Long Wave

Lasers or LEDs that emit light with wavelengths around 1300 nm. Long wave lasers are used for long Fibre Channel links, from approximately 700 to 10,000 m. They are typically used with single-mode fiber of a 9 micron core size.

Loop Address

The unique ID of a node in Fibre Channel loop topology, sometimes referred to as a Loop ID.

Loop Port (L_Port)

An N_Port or F_Port that supports arbitrated loop functions associated with arbitrated loop topology.


A "Node" port. A Fibre Channel defined hardware entity that performs data communication over the Fibre Channel link. It is identifiable by a unique Worldwide Name . It can act as an originator or a responder.

N_Port Identifier

A unique address identifier by which an N_Port is uniquely known. It consists of a Domain (most significant byte), an Area, and a Port, each 1 byte long. The N_Port identifier is used in the Source Identifier (S_ID) and Destination Identifier (D_ID) fields of a Fibre Channel frame.


A physical device that allows for the transmission of data within a network.


The Fibre Channel N_Port responsible for starting and exchange. Fibre Channel term for a SCSI initiator.


One of three existing Fibre Channel topologies, in which two devices are directly connected by a link with no fabric, loop, or switching elements present.


The hardware entity that connects a device to a Fibre Channel topology. A device can contain one or more ports.


Formal set of rules governing the format, timing, sequencing, and error control of exchanged messages on a data network; may also include facilities for managing a communications link and /or contention resolution. A protocol may be oriented toward data transfer over an interface, between two logical units directly connected, or on an end-to-end basis between two end users over a large and comple network. Both hardware protocols and software protocols can be defined.


Redundant Array of Independent Disks. A method for configuring multiple disk modules into a logical disk unit, which appears to the host system as a single, contiguous disk module.


Three or more disk modules bound as striped disks (the disk array reads and writes file information with more than one disk at a time). RAID-0 offers enhanced performance by using simultaneous I/O to different modules, but does not intrinsically offer high availability. For high availability, the striped disks can be software mirrored. RAID-0 is not supported and can be accessed only in FE mode.


Even numbers of mirrored disk modules.


A RAID configuration in which four, six, eight, ten, twelve, fourteen, or sixteen disk modules are bound as a mirrored RAID-0 group. The disk modules are mirrored such that one half the disk modules contain user data and the other half contain a disk-by-disk copy of the user data. A RAID-1/0 group combines the speed advantage of RAID-0 with the redundancy advantage of mirroring.


A RAID-3 group in a Hewlett-Packard High Availability Fibre Channel Disk Array must consist of exactly five disk modules, each on a separate internal SE SCSI-2 bus. RAID-3 uses disk striping and a dedicated parity disk, but not hardware mirroring.


A RAID configuration in which from three to sixteen disk modules use disk striping, with high availability provided by parity information distributed on each disk module. The ideal number of disk modules in a RAID-5 group is five.


The logical function in an N_Port responsible for supporting the exchange initiated by the originator in another N_Port. Fibre Channel term for a SCSI target.


Small Computer System Interface. An industry standard for connecting peripheral devices and their controllers to a processor.

SCSI Addressing

A fast/wide SCSI adapter supports up to 16 devices, including itself. Each device has its own unique SCSI address. The SCSI address of a device dictates the devices's priority when arbitrating for the SCSI bus. SCSI address "7" has the highest priority. The next highest priority address is "6" followed by 5, 4, 3, 2, 1, 0, 15, 14, 13, 12, 11, 10, 9, 8, with "8" being the lowest priority address. The fast/wide SCSI adapter is factory set to address "7."

A narrow SCSI adapter supports up to eight devices, including itself. SCSI address "7" has the highest priority followed by 6, 5, 4, 3, 2, 1, and 0.


An opening at the back of the SCSI MUX providing connection between the SCSI adapter and the SCSI bus.


Lasers or LEDs that emit light with wavelengths around 780 nm or 850 nm. Short wave lasers are used for Fibre Channel links up to approximately 700 m. They are typically used with multimode fibre. The preferred fibre core size is 50 microns since this fibre has large bandwidth so that the distance is limited by the fibre attenuation. A 62.5 micron core size is also supported for compatibility with existing FDDI installations. Fibre of this type has smaller bandwidth and, in this case, the distance is limited by the fibre bandwidth.

See [ Storage-Control Processor (SP) ]
Storage-Control Processor (SP)

A printed-circuit board with memory modules that control the disk modules in the storage system chassis. The SP runs Grid Manager, which is used to bind and unbind logical disk units, set up disk array caching, observe array status, and view the SP event log. The SP in a disk array divides the multiplexed SCSI-2 bus traffic from the host into five internal, single-ended, SCSI-2 buses (identified by the letters A, B, C, D, and E). Each internal SCSI-2 bus supports multiple logical disk units (LUNs).


The physical layout of devices on a network. The three Fibre Channel topologies are fabric, arbitrated loop, and point-to-point. The disk array's default topology is arbitrated loop.


Fibre Channel for Mass Storage
Fibre Channel for Mass Storage
EAN: 2147483647
Year: 1999
Pages: 53 © 2008-2017.
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