RAID, which is short for Redundant Array of Independent Disks, is a software or hardware storage virtualization technology that allows a system to take advantage of a number of 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 in the event that one drive breaks down, the information will be accessible through the others, and the second one is better performance as the input/output, or reading/writing operations will be distributed among multiple drives. There are different RAID types based on what number of drives are employed, whether reading and writing are both performed from all drives at the same time, if data is written in blocks on one drive after another or is mirrored between drives in the same time, and so on. Depending on the particular setup, the fault tolerance and the performance may differ.