RAID, or Redundant Array of Independent Disks, is a technology of storing data on multiple hard disk drives that work together as one single logical unit. The drives could be physical or logical i.e. in the latter case one single drive is split into independent ones via virtualization software. In either case, the same info is stored on all drives and the key advantage of employing this kind of a setup is that in case a drive fails, the data shall still be available on the other ones. Having a RAID also enhances the overall performance as the input and output operations will be spread among several drives. There are several kinds of RAID based on how many drives are used, whether writing is carried out on all drives in real time or just on one, and how the info is synchronized between the drives - whether it's written in blocks on one drive after another or all of it is mirrored from one on the others. All of these factors mean that the fault tolerance as well as the performance between the different RAID types may vary.
RAID in Shared Web Hosting
The disk drives which we use for storage with our revolutionary cloud web hosting platform are not the traditional HDDs, but high-speed solid-state drives (SSD). They operate in RAID-Z - a special setup developed for the ZFS file system that we work with. All the content that you upload to your shared web hosting account will be saved on multiple hard disks and at least one will be employed as a parity disk. This is a specific drive where an additional bit is added to any content copied on it. In case a disk in the RAID stops working, it will be replaced without service disruptions and the data will be rebuilt on the new drive by recalculating its bits thanks to the data on the parity disk along with that on the remaining disks. This is done to guarantee the integrity of the data and along with the real-time checksum verification which the ZFS file system executes on all drives, you'll never need to worry about the loss of any data no matter what.