From the status update you just made on Facebook, to the resume you just uploaded, the information needs to be stored somewhere and that is where data storage and RAID come in.
So what is RAID really? The simplest explanation would be that RAID represents a storage technology that combines multiple disk drive components into one unit for redundancy and improvement of overall performance.
The word RAID first came along in 1987, standing for Redundant Array of Inexpensive Disks.
Today, it is a term used for computer data storage in general and some people refer to it as Redundant Array of Independent Disks. RAID is a good example of storage virtualization.
As has already been mentioned, it was in 1987 that the term, what is RAID today, was first coined at the University of Berkley by David A. Patterson, Garth A. Gibson and Randy Katz. At the time, they were looking at the feasibility of using two or more storage drives, and having those drives appear as only one drive to the host system. They published a paper titled “A Case For Redundant Arrays of Inexpensive Disks (RAID)”
There are several RAID levels, typically 0 to 6 and sometimes involving combinations of these basic levels, all which have their own characteristics, usages and benefits.
What Is RAID Mainly Used For?
There are three main purposes of RAID: capacity, security and performance.
- Capacity: This can involve taking two hard drives that are linked together in order to create one drive from the operating system’s point of view, making a virtual drive that has double the total capacity.
- Performance: Just like two drives can be used as a single drive, the controller can divide a data chunk into dual parts, and each part can then be put on a separate drive. This doubles the read and writing of data performance speed.
- Data Security: Space on one drive is used to clone data that is written on both drives. Therefore, if one drive happens to fail, the other drive will still have the data that is needed.
RAID systems that are used as a secondary storage are not a good alternative to backing up data that is sensitive or important. In RAID levels from 1 to 6, the RAID protects from data loss through physical damage or drive errors on one drive, or two on RAID 6.
A true backup system though, has features that are important including being able to restore to data of an earlier version. This protects against software errors and unwanted data, as well as recovery from an error by the user. With RAID, it is possible for there to be a substantial failure that goes beyond the point where data can be recovered.
In addition, backups can be stored off site and protected from damage, while RAID arrays are at risk for physical damage because they are located within the computer itself. RAID is also exposed to the potential risk of controller failure.
RAID Versus Other Methods
What is RAID also heavily used in is enterprise storage devices and is found in high-capacity storage devices on the consumer market as well. There are other options available to consumers and businesses who do not want to use RAID though, they include:
- JBOD: Literally called “Just A Bunch of Drives“, this alternative uses multiple disks and each disk is addressed separately. This provides increased storage but does not give the fault tolerance of RAID, nor does it enable the performance benefits seen with RAID.
- Spanning: This alternative combines multiple drives to mimic one drive, increasing storage capacity. Once again, compared with RAID, it does not have the reliability or the speed that is seen with RAID.
So by trying to answer that simple question What Is RAID, you end up discovering that, in many ways, our modern computing world could not exist without RAID – especially on the enterprise level used by small and large sized organizations.