Hitachi CBL, Hardware Service Manual

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Glossary–4
Hitachi Unified Storage Hardware Service Guide
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A B C D E F G H I
J K
L M
N O
P
Q
R S T U V W
X Y
Z
CRC
Cyclic Redundancy Check. An error-correcting code designed to detect
accidental changes to raw computer data.
D
Disaster recovery
A set of procedures to recover critical application data and processing
after a disaster or other failure. Disaster recovery processes include
failover and failback procedures.
DMLU
See Differential Management-Logical Unit.
Drive Box
Chassis for mounting drives that connect to the Controller Box.
• Drive Boxes with AC power supply:
DBS, DBL, DBF: Drive Box (2U)
DBX: Drive Box (4U)
DBW: Drive Box (5U)
• Drive Boxes with DC power supply:
DBSD Drive Box (2U)
DBLD: Drive Box (2U)
Drive I/O Module
I/O module for the CBL that has drive interfaces.
Duplex
The transmission of data in either one or two directions. Duplex modes
are full-duplex and half-duplex. Full-duplex is the simultaneous
transmission of data in two direction. For example, a telephone is a full-
duplex device, because both parties can talk at once. In contrast, a
walkie-talkie is a half-duplex device because only one party can
transmit at a time.
E
Ethernet
A computer networking technology for local-area networks.
Extent
A contiguous area of storage in a computer file system that is reserved
for writing or storing a file.