RAID

RAID - REDUNDANT ARRAYS OF INDEPENDENT DISKS

A disk array is an arrangement of several disks together. organized  so as to increase the performance and improve reliability storage system. 

  In simple words, performance is increased through data stripping because  it distributes data over several disks to give the impression of having a single large, very fast disk. But Reliability is improved part redundancy because instead of having single copy of the data. redundant (duplicate or copy) information is painted so that in case  of a disk failure, it can be used to reconstruct the contents of the failed disk.

          Therefore, in short, disk arrays that implements a combination of both i.e., data stripping and redundancy are called as "Redundant Arrays of independent disks", or in short, "RAID" to improve both i.e., performance and Reliability respectively.

           several RAID organizations, referred to as RAID levels, have been proposed. Each RAID level represents a different trade off between reliability and performance as follows.

Data Stripping 

Data stripping is the process where a single large file is divided into a small - small equal pieces and stores these piece of a file on different disks.

Data stripping uses parallelism to improve disk performance by distributing data over multiple disks to make them appear as a single large, fast disk. stripping improves overall Input/Output

performance by allowing multiple Input/Output to be serviced in parallel, thus providing high overall transfer rates. Data stripping also accomplishes load balancing among disks.