RAID, or Redundant Array of Independent Disks, is a technology for storing data on multiple hard disk drives which function together as one logical unit. The drives could be physical or logical i.e. in the latter case one drive is split into separate ones through virtualization software. Either way, the same data is kept on all the drives and the key benefit of employing such a setup is that in case a drive fails, the data shall still be available on the other ones. Employing a RAID also enhances the overall performance because the input and output operations will be spread among a few drives. There are several types of RAID based on how many drives are used, whether writing is done on all the drives in real time or just on a single one, and how the info is synchronized between the drives - whether it is recorded in blocks on one drive after another or it is mirrored from one on the others. All these factors suggest that the error tolerance as well as the performance between the different RAID types can vary.
RAID in Hosting
The hard disks which we employ for storage with our revolutionary cloud Internet hosting platform are not the classic HDDs, but extremely fast solid-state drives (SSD). They function in RAID-Z - a special setup intended for the ZFS file system which we work with. All the content that you upload to your hosting account will be held on multiple hard disks and at least one of them shall be used as a parity disk. This is a specific drive where an extra bit is added to any content copied on it. In case a disk in the RAID stops functioning, it'll be changed with no service interruptions and the information 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 together with the real-time checksum validation which the ZFS file system executes on all drives, you will never need to worry about the loss of any information no matter what.