RAID, which is short for Redundant Array of Independent Disks, is a software or hardware storage virtualization technology which enables a system to use several hard drives as one single logical unit. To put it differently, all drives are used as one and the data on all of them is the same. This type of a configuration has 2 major advantages over using a single drive to save data - the first is redundancy, so if one drive doesn't work, the info will be accessed through the remaining ones, and the second is improved performance since the input/output, or reading/writing operations will be spread among a number of drives. There are different RAID types in accordance with what number of drives are employed, whether reading and writing are both done from all drives simultaneously, whether data is written in blocks on one drive after another or is mirrored between drives in the same time, etc. Determined by the exact setup, the error tolerance and the performance may differ.
