IBM TotalStorage DS4800, Инструкция по установке, эксплуатации и обслуживанию

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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 DS4000 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. A drive 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 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 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). 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 service module
canister .
automatic ESM firmware synchronization. When
you install a new ESM into an existing storage
expansion enclosure in a DS4000 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. See storage expansion enclosure .
expansion port (E_port). A port that connects the
switches for two fabrics.
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 .
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
Glossary
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