Redundant Array of Independent Disks, or RAID, is a method of keeping content on a number of hard drives at the same time. A RAID could be software or hardware depending on the drives which are used - physical or logical ones, still what is common between them is the fact that they all work as just one single unit where info is stored. The main advantage of using a RAID is redundancy as the information on all the drives will be the same all the time, so even in the event that one of the drives fails for some reason, the information will still be present on the other drives. The overall performance is also better because the reading and writing processes could be split between multiple drives, so a single one won't be overloaded. There're different kinds of RAIDs where the capabilities and fault tolerance may vary based on the exact setup - whether information is written on all drives real-time or it's written on one drive and afterwards mirrored on another, what number of drives are used for the RAID, etcetera.
RAID in Cloud Website Hosting
The disk drives that we use for storage with our outstanding cloud web hosting platform are not the classic HDDs, but super fast solid-state drives (SSD). They work in RAID-Z - a special setup developed for the ZFS file system which we employ. Any content that you add to your cloud website hosting account will be saved on multiple disk drives and at least one shall be used as a parity disk. This is a special drive where an extra bit is included to any content copied on it. In case a disk in the RAID stops working, it'll be replaced without any service interruptions and the info will be rebuilt on the new drive by recalculating its bits using the data on the parity disk plus that on the other disks. This is done to guarantee the integrity of the info and together with the real-time checksum verification that the ZFS file system executes on all drives, you'll never need to worry about losing any data no matter what.