IBM DCS3860, Инструкция по установке, использованию и обслуживанию

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direct access storage device (DASD)
A device in which access time is
effectively independent of the location of
the data. Information is entered and
retrieved without reference to previously
accessed data. (For example, a disk drive
is a DASD, in contrast with a tape drive,
which stores data as a linear sequence.)
DASDs include both fixed and removable
storage devices.
direct memory access (DMA)
The transfer of data between memory and
an input/output (I/O) device without
processor intervention.
disk array controller (dac)
A disk array controller device that
represents the two controllers of an array.
See also
disk array router .
disk array router (dar)
A disk array router that represents an
entire array, including current and
deferred paths to all logical unit numbers
(LUNs) (hdisks on AIX
®
). See also disk
array controller .
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.
drive channels
The DS4200, DS4700, DS4800, and DS5000
systems 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/DS5000 storage
systems 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. 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 systems 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 .
Glossary
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