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.

Chapter 2 Introduction to RAID

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