VERITAS Volume Manager 3.1 Reference Guide

Table Of Contents

Chapter 3 109

Disk Arrays

Disk Array Overview

This section provides an overview of traditional disk arrays.

Performing I/O to disks is a slow process because disks are physical

devices that require time to move the heads to the correct position on the

disk before reading or writing. If all of the read or write operations are

done to individual disks, one at a time, the read-write time can become

unmanageable. Performing these operations on multiple disks can help

to reduce this problem.

disk array

is a collection of disks that appears to the system as one or

more virtual disks (also referred to as

volumes

). The virtual disks

created by the software controlling the disk array look and act (to the

system) like physical disks. Applications that interact with physical

disks should work exactly the same with the virtual disks created by the

array.

Data is spread across several disks within an array, which allows the

disks to share I/O operations. The use of multiple disks for I/O improves

I/O performance by increasing the data transfer speed and the overall

throughput for the array.

Figure 3-1, “Standard Disk Array,” shows a standard disk array.