Understanding Drive Arrays; What Is A Drive Array - Compaq Smart Array 221 User Manual

Appendix C

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 Array 221 Controller. Before you configure your Smart Array 221
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 C-1 consists of two logical drives
spread across three physical drives. Figures C-2 through C-4 illustrate other
drive array configurations.
Daz-9-12.EPS
Figure C-1. Drive Array with two logical drives
Writer: Karen Hale Project: Compaq Smart Array 221 Controller User Guide Comments: 388541-001
Physical Physical
Drive 1 Drive 2
Drive Array
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COMPAQ CONFIDENTIAL - NEED TO KNOW REQUIRED
Physical
Drive 3
Logical
Drive 1
Logical
Drive 2
Compaq Smart Array 221 Controller User Guide
C-1