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→An Overview of RAID 5
== An Overview of RAID 5 ==
RAID 5 consists of three or more volumes each located on a separate physical drivedisk. As with RAID 0, RAID 5 also uses disk striping, whereby blocks of data are divided up into stripes with each stripe written to a different disk. RAID 5, however, differs quite considerably from RAID 0. Under RAID 5, not only are the data stripes written, but also parity information relating to the data. The key to RAID 5 fault tolerance is the fact that the parity information for a particular data stripe is always written to a different drive from the drive containing the corresponding data stripe. This means that if a disk fails, the corresponding parity information stored on another disk can be used for error detection and data correction (also referred to as ''regeneration'').
Whilst RAID 5 has considerable advantages over RAID 0 there are one or two drawbacks that should be taken into consideration when considering this storage option. Firstly, there is the inevitable performance overhead inherent in calculating and storing parity information for each data stripe written to disk. Secondly, the loss of more than own disk in a RAID array will be insufficient parity data on the remaining disks to regenerate the original data. That said, RAID 5 does provide considerable advantages that generally outweigh the disadvantages.
