IBM System Storage DS4000, Hardware Maintenance Manual

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DMA. See direct memory access .
domain. The most significant byte in the node port
(N_port) identifier for the fibre-channel (FC) device. It
is not used in the fibre channel-small computer system
interface (FC-SCSI) hardware path ID. It is required to
be the same for all SCSI targets logically connected to
an FC adapter.
DRAM. See dynamic random access memory .
Dynamic Host Configuration Protocol (DHCP). A
protocol defined by the Internet Engineering Task Force
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). A type 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 services monitor (ESM) canister. A
component in a drive 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). A method 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. See environmental services monitor
canister .
EXP.
See expansion unit .
expansion port (E_port). A port that connects the
switches for two fabrics.
expansion unit (EXP). A feature that can be connected
to a system unit to provide additional storage and
processing capacity.
Extended Industry Standard Architecture (EISA). A
bus standard for IBM compatibles that extends the
Industry Standard Architecture (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. A Fibre 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. See also fabric .
FAStT MSJ. See FAStT Management Suite Java .
FAStT Management Suite Java (FAStT MSJ). A
diagnostic and configuration utility that can be used on
Linux, Microsoft Windows, and Novell NetWare host
systems. In Linux, it is also used with the QLRemote
agent to define preferred and non-preferred paths for
logical drives.
FC. See fibre channel .
FC-AL. See arbitrated loop .
feature enable identifier. A unique identifier for the
storage subsystem, which is used in the process of
generating a premium feature key. See also premium
feature key .
fibre channel (FC). A set of standards for a serial
input/output (I/O) bus capable of transferring data
between two ports at up to 100 Mbps, with standards
proposals to go to higher speeds. FC supports
point-to-point, arbitrated loop, and switched topologies.
Fibre Channel-Arbitrated Loop (FC-AL). See arbitrated
loop .
Fibre Channel Protocol (FCP) for small computer
system interface (SCSI). A high-level fibre-channel
mapping layer (FC-4) that uses lower-level
fibre-channel (FC-PH) services to transmit SCSI
commands, data, and status information between a
SCSI initiator and a SCSI target across the FC link by
using FC frame and sequence formats.
Glossary
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