LSI MegaRAID SCSI 320-2 RAID Controller Series 518 - Manual (Page 25)

MegaRAID SCSI 320-2 Hardware Guide 2-1
Copyright © 2002 by LSI Logic Corporation. All rights reserved.
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.
2.1 RAID 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.
2.1.1 Improved 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.