RAID Explained

RAID stands for Redundant Array of Inexpensive (Independent) Disks.

On most situations you will be using one of the following four levels of RAIDs.

    RAID 0
    RAID 1
    RAID 5
    RAID 10 (also known as RAID 1+0)

This article explains the main difference between these raid levels along with an easy to understand diagram.

In all the diagrams mentioned below:

    A, B, C, D, E and F – represents blocks
    p1, p2, and p3 – represents parity

RAID LEVEL 0

    Minimum 2 disks.
    Excellent performance ( as blocks are striped ).
    No redundancy ( no mirror, no parity ).
    Don’t use this for any critical system.
 
 RAID LEVEL 1

    Minimum 2 disks.
    Good performance ( no striping. no parity ).
    Excellent redundancy ( as blocks are mirrored )

RAID LEVEL 5

    Minimum 3 disks.
    Good performance ( as blocks are striped ).
    Good redundancy ( distributed parity ).
    Best cost effective option providing both performance and redundancy.
    Use this for DB that is heavily read oriented. Write operations will be slow.

RAID LEVEL 10

   
     

    Minimum 4 disks.
    This is also called as “stripe of mirrors”
    Excellent redundancy ( as blocks are mirrored )
    Excellent performance ( as blocks are striped )
    If you can afford the dollar, this is the BEST option for any mission critical applications  (especially  databases).