RAID, which is short for Redundant Array of Independent Disks, is a software or hardware storage virtualization technology that makes it possible for a system to employ a number of hard drives as one single logical unit. In other words, all of the drives are used as one and the information on all of them is the same. This kind of a setup has two major advantages over using just a single drive to store data - the first is redundancy, so in the event that one drive doesn't work, the information will be accessed from the others, and the second is improved performance since the input/output, or reading/writing operations will be distributed among several drives. There're different RAID types in accordance with how many drives are used, if reading and writing are both executed from all the drives concurrently, if data is written in blocks on one drive after another or is mirrored between drives in the same time, etcetera. Determined by the particular setup, the error tolerance and the performance may vary.
RAID in Website Hosting
The hard drives which we use for storage with our state-of-the-art cloud Internet hosting platform are not the standard HDDs, but super fast solid-state drives (SSD). They work in RAID-Z - a special setup intended for the ZFS file system that we employ. Any content that you upload to your website hosting account will be saved on multiple drives and at least one shall be employed as a parity disk. This is a special drive where a further bit is added to any content copied on it. In case a disk in the RAID stops working, it will be changed without any service interruptions and the info will be recovered on the new drive by recalculating its bits using the data on the parity disk plus that on the remaining disks. This is done to guarantee the integrity of the data and along with the real-time checksum authentication which the ZFS file system executes on all drives, you won't ever need to concern yourself with losing any data no matter what.