American Megatrends MegaRAID Express 500 - Manual (Page 19)

Chapter 2 Introduction to RAID 5
2 Introduction to RAID
RAID (Redundant Array of Independent Disks) is an array of multiple
independent hard disk drives that provide high performance and fault tolerance.
A RAID disk subsystem improves I/O performance over a computer using only a
single drive. 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 improve data storage reliability and
fault tolerance compared to single-drive computers. Data loss because of a disk
drive failure can be recovered by reconstructing missing data from the remaining
data and parity drives.
RAID Benefits
RAID has gained popularity because it improves I/O performance and increases
storage subsystem reliability. RAID provides data security through fault
tolerance and redundant data storage. The MegaRAID Express 500 management
software configures and monitors RAID disk arrays.
Improved I/O Although disk drive capabilities have improved drastically, actual performance
has been improved only three to four times in the last decade. Computing
performance has been improved over 50 times during the same time period.
Increased Reliability The electromechanical components of a disk subsystem operate more
slowly, require more power, and generate more noise and vibration than
electronic devices. These factors reduce the reliability of data stored on disks.