Chapter 2

Introduction to RAID

This chapter introduces important RAID concepts. It contains the following sections:

•Section 2.1, “RAID Benefits”

•Section 2.2, “MegaRAID SCSI 320-2 – Host-Based RAID Solution”

•Section 2.3, “RAID Overview”

RAID (Redundant Array of Independent Disks) is a data storage method in which data, along with parity information, is distributed among two or more hard disks (called an array) to improve performance and reliability. The RAID array appears to the host computer as a single storage unit or as multiple logical units. I/O is expedited because several disks can be accessed simultaneously. RAID systems provide improved data storage reliability and fault tolerance compared to single-drive computers. If a disk drive in a RAID array fails, data can be reconstructed from the data and parity information on the remaining disk drives.

2.1RAID Benefits

RAID is widely used because it improves I/O performance and increases storage subsystem reliability. RAID provides data security through fault tolerance and redundant data storage. The MegaRAID SCSI 320-2 management software configures and monitors RAID disk arrays.

2.1.1Improved I/O

Although disk drive capabilities have improved drastically, actual performance of individual disk drives has been improved only three to four times in the last decade. RAID provides a way to achieve much better data throughput.

MegaRAID SCSI 320-2 Hardware Guide

2-1

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