User guide

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 Array 431 Controller. Before you configure your Smart Array 431
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.