Operating System Design/File Systems/RAID
RAID (Redundant Array of Independent Disks) is a method of storing data combines multiple physical drives into one unit. Data is distributed and duplicated across the drives in various ways. The term has now come to mean any technology that divides and replicates data over multiple drives. The main advantages is in reliability: depending on the RAID level, there is a certain amount of data redundancy, which allows there to be faults and errors without data being lost.