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RAID explained

by Mathew .. on 28 July 2005, 00:00

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In this guide we will be examining a popular method used for increasing the performance and reliability of your hard drives and data storage.

RAID stands for Redundant Array of Inexpensive Disks. RAID, which can be implemented through hardware, software, or a combination of the two, takes multiple physical disks and combines them into a single, 'virtual' disk. The way in which RAID is implemented affects the benefits that RAID provides.

There are a great many implementations of RAID, the most common of which are discussed in this guide. For the desktop user several of these types will not apply, so most users should concentrate on RAID 0+1/1+0 or RAID 5; the others are included for background information or as an aside.

A general rule of any RAID setup is that drives in the array should be identical. If different sized drives are used, you may find all the drives will be considered to be size of the smallest drive present. Speed is determined in a similar fashion; if three 7,200rpm drives are used along with one 5,400rpm drive, the array will be limited by the slowest device.

On the following pages we will go over the various types of RAID and the principles behind them. As this is intended to be a brief overview of a large topic, some of the more detailed facets of the background have been omitted. These RAID types apply to PATA, SATA and SCSI devices.