What's RAID All About?

RAID stands for Redundant Array of Inexpensive Disks. However, some prefer to define RAID as Redundant Array of Independent Disks. In principle, RAID is a technique in which you logically turn two or more hard disks into a single, high performance hard disk. How this is done depends on which RAID level is used.

Well, there is quite a lot to talk about regarding RAID as a whole. However, I'll try to keep it short and simple, and yet informative enough so that even newbies will be able to understand the concept of RAID as well as how, when and why it can improve the hard disk performance.

Now, there are different kinds of RAID, called RAID levels. Each RAID level has its advantages and disadvantages. The higher the level, the higher the cost. Let me introduce each of the RAID levels to you before I continue.

RAID Level	Description	Diagram
0	Non-Redundant, Striping
1	Mirroring
2	Bit-level striping with Hamming code error correction.
3	Byte-level striping with dedicated parity
4	Block-level striping with dedicated parity
5	Block-level striping with distributed parity
6	Block-level striping with dual distributed parity