RAID

What is RAID And What Are The Benefits

RAID stands for Redundant Array of Independent Disks and is a technology that has been around for many years and is commonly found in small and medium businesses as well as high performance computers. A RAID array only appears as a single drive on a computer when in fact it is made up of two or more hard drives.

There are 3 main types of RAID array. Let’s look at the these three common RAID types and their advantages and disadvantages.

RAID 0

RAID 0 also known as Striping and offers no redundancy but is known to be better performing type of RAID. It uses all of your drives to create one huge drive. For example if you had 2X250GB drives setup as a RAID 0 your computer would show a drive that is around about 500GB.

A very simple example with 2x250GB hard drives. If we take the phrasecomputerlearnhow.com this is how it could look on a RAID 0

Drive Capacity: 500GB

Disc 1: c,m,u,e,l,a,n,o,.,o

Disc 2: o,p,t,r,e,r,h,w,c,m

You can see how no disk holds the complete phrase it is split over the 2 disks.

Advantages

RAID 0 offers a performance increase as data is written to both physical drives (split in half essentially) This means that you are doubling the speed at which the data is written to the drive as the computer can write to both drives at the same time.

Disadvantages

The huge disadvantage of RAID 0 is that there is no redundancy so data is not backed up. If one hard drive became corrupted or damaged in any way you will essentially lose the data as your it is split between both drives. This means that there is a greater chance for failure as you are relying on both drives functioning correctly.

RAID 1

RAID 1 is also referred to as mirroring and it is exactly as you would expect. The data on drive 1 is duplicated on drive 2 so you have 2 drives containing exactly the same data. This is the recommended setup for dual drives if capacity and speed are not as crucial as redundancy.

A very simple example with 2x250GB hard drives. If we take the phrasecomputerlearnhow.com this is how it would look on a RAID 1

Drive Capacity: 250GB

Disc 1: computerlearnhow.com

Disc 2: computerlearnhow.com

Advantages

The huge advantage of RAID 1 is that the drive is always mirrored meaning that if one drive fails you have the data on the second drive. If drive A fails drive B takes over as the primary drive and once drive A is swapped out it returns to a RAID 1. It is an excellent way of ensuring data is not lost and is a great way to backup your files

Disadvantages

There are 2 disadvantages over the RAID 0 system. The first is the performance will be slower than RAID 0 as you are not doubling the speed  with redundancy. The second is that capacity is lower. If you have 2 X 250GB drive in a RAID 1 you are only ever really using one the second drive is used to mirror the first. In this case it is just as good to use an external hard drive to backup your files.

RAID 5

To have a RAID 5 configuration you would need at least 3 hard drives. RAID 5 is a little more difficult to explain than the other 2. It writes data to several drives and distributes parity bits across all drives meaning even if one drive fails the other 2 drives still function correctly. The best way I have seen it put is that the parity information is the C in the equation A+B=C. You can lose any of them and you would still be able to piece together the data from the 2 remaining.

A very simple example with 3x250GB hard drives. If we use ABCDEF this is how it would look on a RAID 5 (p= parity bit)

Drive Capacity: 500GB

Disc 1: A,C,p3

Disc 2: B,p2,E

Disc 3: p1,D,F

Advantages

Because RAID 5 stripes data performance is increased and you also have your redundancy. Storage is also increased.

Disadvantages

If 2 disks are lost as the same time then data is lost but apart from that the only other downside is it does require someone with technical knowledge to keep an eye on the system

(Courtesy: bnjho.blogspot.com)