RAID Explained!

Whether you're looking to optimize performance on your small business server or you just want to defend against total data loss on a NAS box, you need RAID. But what the heck is it, and which RAID do you need? RAID 0? RAID 1? RAID 10? Don't worry, we'll help you pick.
Anyone who's ever looked into purchasing a NAS device or server, particularly for a business, has inevitably stumbled across the term "RAID." RAID stands for Redundant Array of Inexpensive or (the more marketing-friendly "Independent) Disks." In general, RAID uses two or more hard disk drives to improve the performance or provide some level of fault tolerance for a machine
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

Following are the key points to remember for 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

Following are the key points to remember for RAID level 1.
Minimum 2 disks.
Good performance ( no striping. no parity ).
Excellent redundancy ( as blocks are mirrored ).


RAID LEVEL 5

Following are the key points to remember for 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

Following are the key points to remember for 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). 


Other RAID Levels

There are other RAID levels: 2, 3, 4, 7, 0+1...but they are really variants of the main RAID configurations already mentioned and used for specific instances.
Here are some short descriptions of each:

RAID 2 is similar to RAID 5, but instead of disk striping using parity, striping occurs at the bit-level. RAID 2 is seldom deployed because costs to implement are usually prohibitive (a typical setup requires 10 disks) and gives poor performance with some disk I/O operations.
RAID 3 is also similar to RAID 5, except this solution requires a dedicated parity drive. RAID 3 is seldom used but in the most specific types of database or processing environments that would benefit from it.
RAID 4 is similar to RAID 3 except disk striping happens at the byte level, rather than the bit-level as in RAID 3.
RAID 7 is a proprietary level of RAID owned by the now-extinct Storage Computer Corporation.



I hope my explanation  could help to to get a better idea of the various Redundant Arrays Of Disks..

Leave your queries down below the comment section
Share this post if you like it
You can follow me on G+,FB and Twitter!
Thank You :)