IBM DS5020 - page 235

interface (FC-SCSI) hardware path ID. It is required to

be the same for all SCSI targets logically connected to

an Fibre Channel adapter.

drive channels. The DS4200, DS4700, and DS4800

subsystems use dual-port drive channels that, from the

physical point of view,are connected in the same way

as two drive loops. However,from the point of view of

the number of drives and enclosures, they are treated

as a single drive loop instead of two different drive

loops.A group of storage expansion enclosures are

connected to the DS5020 storage subsystems using a

drive channel from each controller.This pair of drive

channels is referred to as a redundant drive channel

pair.

drive loops. Adrive loop consists of one channel from

each controller combined to form one pair of redundant

drive channels or a redundant drive loop. Each drive

loop is associated with two ports. (There are two drive

channels and four associated ports per controller.)For

the DS4800, drive loops are more commonly referred to

as drive channels. See drive channels.

DRAM. See dynamic random access memory.

Dynamic Host Configuration Protocol (DHCP). A

protocol defined by the Internet Engineering TaskForce

that is used for dynamically assigning Internet Protocol

(IP) addresses to computers in a network.

dynamic random access memory (DRAM). A

storage in which the cells require repetitive application

of control signals to retain stored data.

ECC. See error correction coding.

EEPROM. See electrically erasable programmable

read-only memory.

EISA. See Extended Industry Standard Architecture.

electrically erasable programmable read-only

memory (EEPROM). Atype of memory chip which can

retain its contents without consistent electrical power.

Unlike the PROM which can be programmed only once,

the EEPROM can be erased electrically.Because it can

only be reprogrammed a limited number of times before

it wears out, it is appropriate for storing small amounts

of data that are changed infrequently.

electrostatic discharge (ESD). The flow of current

that results when objects that have a static charge

come into close enough proximity to discharge.

environmental service module (ESM) canister. A

component in a storage expansion enclosure that

monitors the environmental condition of the components

in that enclosure. Not all storage subsystems have ESM

canisters.

E_port. See expansion port.

error correction coding (ECC). Amethod for

encoding data so that transmission errors can be

detected and corrected by examining the data on the

receiving end. Most ECCs are characterized by the

maximum number of errors they can detect and correct.

ESD. See electrostatic discharge.

ESM canister. Seeenvironmental service module

canister.

automatic ESM firmware synchronization. When

you install a new ESM into an existing storage

expansion enclosure in a storage subsystem that

supports automatic ESM firmware synchronization, the

firmware in the new ESM is automatically synchronized

with the firmware in the existing ESM.

EXP. Seestorage expansion enclosure.

expansion port (E_port). Aport that connects the

switches for two fabrics.

Extended Industry Standard Architecture (EISA). A

bus standard for IBM compatibles that extends the

Industry StandardArchitecture (ISA) bus architecture to

32 bits and allows more than one central processing

unit (CPU) to share the bus. See also Industry Standard

Architecture.

fabric. AFibre Channel entity which interconnects and

facilitates logins of N_ports attached to it. The fabric is

responsible for routing frames between source and

destination N_ports using address information in the

frame header.A fabric can be as simple as a

point-to-point channel between two N-ports, or as

complex as a frame-routing switch that provides multiple

and redundant internal pathways within the fabric

between F_ports.

fabric port (F_port). In a fabric, an access point for

connecting a user’s N_port.An F_port facilitates N_port

logins to the fabric from nodes connected to the fabric.

An F_port is addressable by the N_port connected to it.