LSI 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.