Redundant Array of Independent Disks, or RAID, is a way of saving content on several hard disks simultaneously. A RAID could be software or hardware based on the HDDs which are used - physical or logical ones, yet what’s common between them is the fact that they all operate as just a single unit where info is kept. The top advantage of using a RAID is redundancy since the data on all the drives shall be the same at all times, so even in the event that one of the drives fails for whatever reason, the data will still be present on the rest of the drives. The overall performance is enhanced as well as the reading and writing processes will be split between a number of drives, so a single one can't be overloaded. There are different types of RAIDs where the capabilities and fault tolerance could differ depending on the exact setup - whether your data is written on all of the drives real-time or it's written on a single drive and after that mirrored on another, what amount of drives are used for the RAID, and so on.
RAID in Web Hosting
The drives which we use for storage with our innovative cloud hosting platform are not the standard HDDs, but high-speed solid-state drives (SSD). They function in RAID-Z - a special setup created for the ZFS file system which we employ. All the content that you add to the web hosting account will be kept on multiple hard disks and at least one of them shall be used as a parity disk. This is a special drive where a further bit is included to any content copied on it. In case a disk in the RAID stops working, it will be changed with no service disruptions and the data will be rebuilt on the new drive by recalculating its bits using the data on the parity disk along with that on the other disks. This is done to guarantee the integrity of the information and together with the real-time checksum validation that the ZFS file system executes on all drives, you won't ever have to worry about losing any information no matter what.