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SMART-2DH Array Controller Reference Guide
Writer: Pamela King Project: SMART-2DH Array Controller Reference Guide Comments: 295469-002
File Name: K-APPD.DOC Last Saved On: 2/27/98 12:06 PM
COMPAQ CONFIDENTIAL - NEED TO KNOW REQUIRED
Appendix D
Understanding Drive Arrays
This chapter provides explanations of drive array concepts, data protection
methods including fault tolerance options, and data reliability features of the
SMART-2DH Array Controller. Before you configure your SMART-2DH
Controller, review the following general information so that you will be
familiar with the terms and concepts required for configuration.
What is a Drive Array?
A drive array is simply a collection of hard disk drives or physical drives that
are grouped together to create an array of physical drives. An array is made
up of one or more subsets called logical drives (sometimes called logical
volumes), which are spread across all physical drives in the array. Operating
systems view logical drives as a single, contiguous storage space, although it
is made up of parts of several physical drives.
The generic drive array illustrated in Figure D-1 consists of two logical drives
spread across three physical drives. Figures D-2 through D-4 illustrate other
drive array configurations.
Daz-9-12.EPS
Physical
Drive 1
Physical
Drive 2
Physical
Drive 3
Logical
Drive 1
Logical
Drive 2
Drive Array
Figure D-1.
Drive array with two logical drives