RAID, which stands short for Redundant Array of Independent Disks, is a software or hardware storage virtualization technology that allows a system to employ multiple hard drives as one single logical unit. Put simply, all of the drives are used as one and the data on all of them is identical. This kind of a configuration has 2 key advantages over using a single drive to store data - the first is redundancy, so in case one drive stops working, the data will be accessible through the others, and the second one is better performance because the input/output, or reading/writing operations will be spread among multiple drives. There are different RAID types depending on what number of drives are employed, if reading and writing are both handled from all drives at the same time, whether data is written in blocks on one drive after another or is mirrored between drives in the same time, and so on. According to the particular setup, the error tolerance and the performance could differ.