RAID
RAID, which is an acronym of Redundant Array of Independent Disks, is a software or hardware storage virtualization technology which enables a system to employ multiple hard drives as a single logical unit. Simply put, all of the drives are used as one and the info on all of them is identical. Such a setup has two major advantages over using just a single drive to keep data - the first one is redundancy, so in case one drive stops working, the information will be accessed through the remaining ones, and the second one is improved performance since the input/output, or reading/writing operations will be distributed among different drives. You can find different RAID types in accordance with what amount of drives are employed, whether reading and writing are both executed 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. Based on the particular setup, the fault tolerance and the performance may vary.