RAID, or Redundant Array of Independent Disks, is a technology for saving data on multiple hard disks that operate together as a single logical unit. The drives can be physical or logical i.e. in the aforementioned case one single drive is split into individual ones using virtualization software. In either case, exactly the same data is kept on all the drives and the main advantage of using such a setup is that in case a drive fails, the data will remain available on the other ones. Having a RAID also boosts the 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 drives are used, whether writing is performed on all drives in real time or just on a single one, and how the data is synchronized between the drives - whether it's recorded in blocks on one drive after another or it is mirrored from one on the others. These factors suggest that the fault tolerance as well as the performance between the various RAID types can differ.
RAID in Website Hosting
The hard disks that we employ for storage with our ground-breaking cloud web hosting platform are not the standard HDDs, but high-speed solid-state drives (SSD). They function in RAID-Z - a special setup designed for the ZFS file system which we use. Any content that you upload to the website hosting account will be kept on multiple hard drives and at least one 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 functioning, it will be replaced without any service interruptions 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 data and together with the real-time checksum validation which the ZFS file system performs on all drives, you'll never have to be concerned about losing any info no matter what.