What is RAID?
RAID is a short form of redundant array of independent disks, it was originally called as redundant array of inexpensive disks. RAID is a virtualization technology that combines multiple disk drive components into a standalone logical unit for the purposes of data redundancy or performance enhancements. It provides a way of storing the same data across different places, thus redundantly on multiple hard disks. By storing the data on multiple disks lead to increase the mean time between failures (MTBF), it also increases the fault tolerance, and improve the overall performance.
RAID array appears to the operating system in the form of a single logical hard disk. It employs the technique of data mirroring or disk striping, which comprised of partitioning each drive’s storage space into the units, varying from a sector of 512 bits bytes up to several megabytes. The different schemes or architectures of RAID can be represented in the form of levels (e.g. RAID 0, RAID1). Each scheme of RAID offers a different balance between the main objectives: reliability, performance, availability and capacity. RAID standard levels greater than RAID 0 safeguards against unrecoverable (sector) read errors, and the whole disk failure.