RAID (Redundant Arrays of Independent Disks) –It is an idea in storage subsystems that can deliver enhanced protection against data loss and down-time than conventional disk drives. RAID refers to a drive architecture that is designed to protect critical data through redundancy. In theory, conventional discs which made up the RAID arrays can function for hundred or even thousands of years without losing data because of disc failure. Other benefits of RAID include an improvement in input/output performance, allowing users to fine-tune drive systems to match the needs of specific applications and making servicing quicker and simpler.