RAID Basics

A basic RAID configuration varies depending on what you want to accomplish and how much you want to spend. Remember whatever RAID array you create all the drives in the array need to be of the same size (if not, the larger drives will be limited to the size of smallest drive which is not cost effective at all).

RAID can be configured to Mirror data, to spread the data across multiple drives (striping) or do both. Mirroring data gives you 1 to 1 redundancy but does not contribute to more space or any faster speed. This is called RAID 1. It is much slower than no RAID at all because the data needs to be written twice.

Striping (pronounced stripe-ing not stripping) increases speed and storage size by a factor equal to the number of drives you have in the stripe. This is called RAID 0. This is as fast as you can get because the data that needs to be written or read can be spread across multiple drives.

The best of both worlds is called RAID 5 or Striping with Parity. Parity is a check on a data group to determine if the data sent is still good. Click here for a parity tutorial.

RAID 1 (mirror) requires at least 2 drives.

RAID 0 (stripe) requires at least 2 drives.

RAID 5 (Stripe with Parity) requires at least 3 drives.
This will give a total storage size of (N-1)*(drive size).

	SCSI RAID	IDE RAID
Cost	Thousands	less than $300
Speed	Extremely Fast (320MBps)	Very Fast (133Mbps)
Redundancy	Fully Redundant	Fully Redundant
Usage	Corporate File Servers & Critical Systems	Department File Servers High End Workstations, and Killer Game Boxes!

Article last reviewed: 07/18/2003

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