RAID, or Redundant Array of Independent Disks, is a technology for keeping data on multiple hard disk drives that work together as a single logical unit. The drives could be physical or logical i.e. in the latter case one drive is split into independent ones through virtualization software. In either case, exactly the same information is kept on all the drives and the main benefit of employing such a setup is that in the event that a drive fails, the data shall still be available on the remaining ones. Using a RAID also improves the performance since the input and output operations will be spread among a number of drives. There are several types of RAID dependant upon how many hard disks are used, whether writing is done on all the 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 it is mirrored from one on the others. These factors imply that the fault tolerance and the performance between the various RAID types can vary.
RAID in Shared Website Hosting
The hard drives which we use for storage with our top-notch cloud Internet hosting platform are not the classic HDDs, but quick solid-state drives (SSD). They work in RAID-Z - a special setup developed for the ZFS file system that we use. All of the content that you upload to the shared website hosting account will be saved on multiple hard disks and at least 1 will be used as a parity disk. This is a specific drive where an extra bit is added to any content copied on it. If a disk in the RAID stops working, it will be replaced without service disturbances and the information will be rebuilt on the new drive by recalculating its bits thanks to the data on the parity disk along with that on the other disks. This is done in order to ensure the integrity of the information and along with the real-time checksum validation which the ZFS file system runs on all drives, you will never need to be concerned about the loss of any info no matter what.