RAID, or Redundant Array of Independent Disks, is a technology for saving data on several hard drives that work together as one logical unit. The drives could be physical or logical i.e. in the latter case one drive is divided into individual ones via virtualization software. Either way, the very same info is saved on all drives and the main advantage of using this kind of a setup is that in the event that a drive breaks down, the data will remain available on the remaining ones. Having a RAID also enhances the overall performance as the input and output operations will be spread among a few drives. There are several kinds of RAID based on how many hard disks are used, whether writing is performed on all drives in real time or just on a single one, and how the info is synchronized between the hard drives - whether it's written in blocks on one drive after another or all of it is mirrored from one on the others. All these factors indicate that the fault tolerance as well as the performance between the various RAID types could differ.
RAID in Web Hosting
The drives which we use for storage with our innovative cloud hosting platform are not the traditional HDDs, but fast solid-state drives (SSD). They function in RAID-Z - a special setup intended for the ZFS file system that we use. Any content that you add to the web hosting account will be stored on multiple hard drives and at least one of them will be employed as a parity disk. This is a special drive where a further bit is included to any content copied on it. In case a disk in the RAID stops working, it'll be replaced without 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 remaining disks. This is done so as to guarantee the integrity of the info and together with the real-time checksum authentication that the ZFS file system runs on all drives, you won't ever have to concern yourself with losing any information no matter what.