DHCP
Dynamic Host Configuration Protocol. A
communication protocol that centrally manages
and automates the assignment of IP addresses
on a network.
direct-attached storage
A digital storage system directly attached to a
server or workstation, without a storage network
in between. This term is mainly used to
differentiate non-networked storage from storage
area networks (SAN) and network-attached
storage (NAS).
DNS
See “Domain Name System”.
Domain Name System
A program or computer server that implements a
name-service protocol. It maps a human-
recognizable identifier to a system-internal, often
numeric, identification or addressing component
(usually an IP address).
drive drawer
See “active drawer”.
Dual Controller Non-Redundant (DCNR) mode
A system mode for Nexsan storage systems. In
this mode, both RAID controller are active, but
each controller operates as an independent node,
and all ports are independent from each other.
The volumes can only be mapped to ports on the
controller that owns the Array. They become
inaccessible if the controller fails.
duplex
A communication system where data flows in
both directions between two devices. There are
two configurations. “Half duplex” provides
communication in both directions, but not at the
same time; when one device transmits, the other
device can only receive, and vice versa. For
example, walkie-talkies, police radios, and other
two-way radio systems use half duplex
communication. “Full duplex” allows both
devices to send information simultaneously. For
example, telephones and videoconferencing
systems use full-duplex communication.
E
E-Series
The series of Nexsan units that includes the
Nexsan E18, E48, and E60 storage units (and
their V, VT and P variants), the Nexsan E32V,
and the Nexsan E18X, E48X, and E60X
expansion units (and their XV variants). Nexsan
E-Series units feature Active Drawer
Technology, Anti-Vibration Design, and
CoolDrive Technology.
emergency firmware
In Nexsan storage systems, an extra piece of
firmware that allows the unit to be started up in
emergency mode. Emergency firmware can be
uploaded to the unit at any time without having to
restart.
emergency mode
In Nexsan storage systems, a mode into which
the unit can be started if the main firmware
becomes corrupt and the unit becomes
inaccessible. Emergency mode requires the
presence of emergency firmware. Emergency
mode allows the user to upload new firmware to
the unit so that it can operate normally.
encrypted array
On Nexsan E-Series storage systems, a RAID
array that is entirely composed of self-encrypting
disks (SEDs) and has been encrypted at the
hardware level by using the Configure Array
Encryption page in the graphical user interface
(GUI). User data on disks in an encrypted array
cannot be read without the accompanying
encryption key.
encryption
A technology which protects information by
converting it into unreadable code that cannot be
deciphered easily by unauthorized people.
Accessing encrypted information requires the
use of an encryption key.
encryption key
On Nexsan E-Series storage systems, a data file
(.dat) that allows user data to be read from and
Glossary
Nexsan High-Density Storage
User Guide
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