Logic MegaRAID Express User's Guide

MegaRAID Express 500 Hardware Guide
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Glossary,
Continued
Consistency Check
An examination of the disk system to determine whether all conditions are valid for the
specified configuration (such as parity.)
Cold Swap
A cold swap requires that you turn the power off before replacing a defective hard drive
in a disk subsystem.
Data Transfer Capacity
The amount of data per unit time moved through a channel. For disk I/O,
bandwidth is expressed in megabytes per second (MB/s).
Degraded
A drive that has become non-functional or has decreased in performance.
Disk
A non-volatile, randomly addressable, rewritable mass storage device, including both
rotating magnetic and optical disks and solid-state disks, or non-volatile electronic storage
elements. It does not include specialized devices such as write-once-read-many (WORM)
optical disks, nor does it include so-called RAM disks implemented using software to
control a dedicated portion of a host computer volatile random access memory.
Disk Array
A collection of disks from one or more disk subsystems combined with array management
software. It controls the disks and presents them to the array operating environment as
one or more virtual disks.
Disk Duplexing
A variation on disk mirroring where a second disk adapter or host adapter and redundant
disk drives are present.
Disk Mirroring
Writing duplicate data to more than one (usually two) hard disks to protect against data
loss in the event of device failure. It is a common feature of RAID systems.
Disk Spanning
Disk spanning allows multiple disk drives to function like one big drive. Spanning
overcomes lack of disk space and simplifies storage management by combining existing
resources or adding relatively inexpensive resources. For example, four 400 MB disk
drives can be combined to appear to the operating system as one single 1600 MB drive.
See also Array Spanning and Spanning.
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