What is RAID? & Different Types of RAID

RAID is a very useful data storage Virtualization technology and stands for Redundant Arrays of Independent Disk. RAID is widely used to provide data protection against disk failures and performance. In RAID, multiple disks are combined to form a single set and then the data is stored in it using different RAID levels. This improves performance and/or reliability.


what is RAID


Earlier the term “Independent” in RAID was called inexpensive but due to the technology enhancement, it was given name ‘independent’.


Recommended Article: What is SAN?


RAID concept was laid by the technical paper titled “A Case for Redundant Arrays of Inexpensive Disks (RAID)” submitted in 1987 by David Patterson, Garth Gibson, and Randy H Katz at the University of California, Berkeley. They studied the possibility of using two or more drives to appear as a single device to the host.

The paper presented by them on RAID described the use of small-capacity, inexpensive disk drives
as an alternative to large-capacity drives common on mainframe computers


Different Types of RAID Implementation


We have two types of RAID implementation viz. Hardware and Software. Both these implementation has its own advantages and disadvantages.


Hardware RAID


In simple words, Hardware RAID needs external hardware controller for its implementation. This hardware controller can be on storage disk array or host itself. This implementation differs in the way the storage array and host are interacted.

Example: Controller card RAID

Hardware RAID is more flexible, support all RAID levels and provide better performance than software RAID for large and complex implementations.


Software RAID


Software RAID does not need any hardware for its implementation and uses host-based software to perform RAID functions. They provide cost-effective solutions and simple to use as compared to hardware RAID in a small implementation.

Example: Creating different RAID levels in Linux/Unix

Apart from the merits of software RAID, they have limitations too.

Software RAID does not provide good system performance as addition CPU cycles are required to perform software raid calculations. Thus we have avoided them while working on complex implementation.

It does not support all RAID levels and is not so flexible as depends upon the operating system.

These were the two different types of RAID implementation and we will discuss about different RAID levels like RAID 0, RAID 1, RAID 5, etc. in the next article.

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  1. vinay krishna May 23, 2014
  2. Rishika Soni December 2, 2017
    • ST December 3, 2017

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