RAID is a common term in the world of computers. Perhaps you have come across it when you are deciding to purchase a new computer. Just what is RAID?
RAID, short for Redundant Array of Independent Disks, was a term first coined in 1987. Researchers at the University of California, Berkeley explored solutions to overcome the weaknesses of a single hard disk. At times, the single disk lacked in speed and was unable to run as quickly as the other system components. In the event of a disk failure, all the stored data would be lost too.
It was then the idea of putting and interlinking multiple drives together was birthed. In turn, this array is able to deliver greater performance, capacity and reliability. Data can be read and written at a faster speed while power consumption is also reduced.
A RAID array is set up using a RAID controller. This RAID controller can take the form of a software-based solution as well as internal or external hardware solution. For the software version, all commands are performed using the host's microprocessor. Software RAID is cheaper, although it comes with limited expandability.
An internal hardware controller is either an integrated RAID onboard capability or high-speed host bus slot. Running like a powerful machine, an external hardware controller boasts an inbuilt microprocessor and is capable of performing full RAID operations and data caching.
Benefits of RAID
With RAID, data can be mirrored on all the disks in the same array. Data is duplicated and there are two or more copies of the data written on separate disks. This way, even if one disk fails, the data is still protected. With the parity feature, RAID is able to detect errors. Through analysing the parity bit, the corrupted data can be corrected. The restoration of data is automatic.
Another great feature of RAID is striping, which helps to boost performance. In a striped array, the written data is split into different pieces and then stored on the individual disks. When a request is made to read the data, the pieces are then retrieved and processed by the CPU.
The downside to striping is that similar hard disks must be used. Also, the speed of the slowest drive will determine how long it takes to piece together the original data.
Caveats when using RAID
Because of the mirroring and parity features, many users mistakenly believe that RAID is invincible. As such, they do not bother with regular maintenance and backups. Like all computer components, RAID is susceptible to virus attacks, logical corruption, etc. Successive disk failure can happen and unless the problem is remedied, the RAID could become corrupted, resulting in a loss of data.
It is therefore important to back up your data periodically.