RAID Levels Explained

What is RAID ?

The acronym RAID stands for redundant array of independent disks. To reduce the complexity and failures of Hard Disks, different levels of RAID come into play depending upon the selected level. The following four RAID levels are the mostly utilized.

With the help of proper diagrams, let’s see how each RAID differ from the others. We are about to look at RAID 0, RAID 1, RAID 5 & RAID 10 only.

NOTE: A1, A2 , B1, B2, C1, C2 indicates the blocks on disks & Ap, Bp, Cp shows the parity.

A. RAID 0  – additionally, called ‘disk striping’ is employed for reinforcing server performance. Here the blocks are stripped with no mirror or parity. RAID 0 delivers excellent performance due to blocks being stripped, and no redundancy due to absence of parity and mirroring. Lack of redundancy risks the loss of data in case if even one disk fails.

B. RAID 1 – Known as ‘disk mirroring’ is utilized for copying data from one disk to another. Also, used for mirroring and replica purpose.

RAID 1 doesn’t use striping and parity. It is used for heavy mirroring and where fault tolerance is of utmost importance to be cared of. With RAID 1 data can be copied seamlessly from one drive to another. This mechanism ensures smooth running when in case one drive stops working due to damage, etc.

C. RAID 5 – Widely used for enterprise servers as serves with better performance than mirroring and fault tolerance.

RAID 5 equipped with distributional parity helps in redundancy, and stripping helps in spreading data across minimum 3 disks; the maximal disk number can be 32. Due to combined rate of consisting disks, RAID 5 provides excellent reading rate then compared to writing rate. Additionally, it is cost effective.

D. RAID 10 – Combination of RAID 0 & RAID 1 generates top performance, but is costlier as well.

Minimum of 4 disks required in RAID 10 which is costlier, but reinforces best performance as a result of  RAID 1 mirroring along with striping of RAID 0. Highly suitable and ideal for servers deployed to serve heavy write operations.

That’s all !