Redundant Array of Independent Disks, or RAID, is a way of saving content on a number of hard disk drives at the same time. A RAID can be software or hardware depending on the HDDs that are used - physical or logical ones, however what is common between them is that they all operate as a single unit where data is stored. The key advantage of employing a RAID is redundancy as the data on all of the drives shall be exactly the same at all times, so even in case a drive fails for some reason, the data will still be present on the remaining drives. The overall performance is also enhanced as the reading and writing processes will be split between multiple drives, so a single one will never be overloaded. There are different kinds of RAIDs where the capabilities and fault tolerance could differ according to the specific setup - whether data is written on all the drives real-time or it is written on a single drive and then mirrored on another, what number of drives are used for the RAID, and many others.
RAID in Web Hosting
The hard drives that we use for storage with our innovative cloud web hosting platform are not the traditional HDDs, but high-speed solid-state drives (SSD). They function in RAID-Z - a special setup developed for the ZFS file system that we use. Any content that you upload to the web hosting account will be stored on multiple hard disks and at least 1 will be used as a parity disk. This is a special drive where an extra bit is included to any content copied on it. In the event that a disk in the RAID stops working, it will be changed without 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 remaining disks. This is done in order to ensure the integrity of the data and along with the real-time checksum validation that the ZFS file system executes on all drives, you'll never need to concern yourself with the loss of any data no matter what.