Logic MegaRAID Express User's Guide

MegaRAID Express 500 Hardware Guide
124
Glossary,
Continued
Format
The process of writing zeros to all data fields in a physical drive (hard drive) to map out
unreadable or bad sectors. Because most hard drives are factory formatted, formatting is
usually only done if a hard disk generates many media errors.
GB
Shorthand for 1,000,000,000 (10 to the ninth power) bytes. It is the same as 1,000 MB
(megabytes).
Host-based Array
A disk array with an Array Management Software in its host computer rather than in a
disk subsystem.
Host Computer
Any computer that disks are directly attached to. Mainframes, servers, workstations, and
personal computers can all be considered host computers.
Hot Spare
A stand-by drive ready for use if another drive fails. It does not contain any user data. Up
to eight disk drives can be assigned as hot spares for an adapter. A hot spare can be
dedicated to a single redundant array or it can be part of the global hot-spare pool for all
arrays controlled by the adapter.
Hot Swap
The substitution of a replacement unit in a disk subsystem for a defective one, where the
substitution can be performed while the subsystem is running (performing its normal
functions). Hot swaps are manual.
I/O Driver
A host computer software component (usually part of the operating system) that controls
the operation of peripheral controllers or adapters attached to the host computer. I/O
drivers communicate between applications and I/O devices, and in some cases
participates in data transfer.
Initialization
The process of writing zeros to the data fields of a logical drive and generating the
corresponding parity to put the logical drive in a Ready state. Initializing erases previous
data and generates parity so that the logical drive will pass a consistency check. Arrays
can work without initializing, but they can fail a consistency check because the parity
fields have not been generated.
Cont’d