RAID, or Redundant Array of Independent Disks, is a technology for saving data on multiple hard drives which function together as one logical unit. The drives could be physical or logical i.e. in the aforementioned case one single drive is divided into different ones using virtualization software. In any case, identical information is stored on all drives and the key advantage of using such a setup is that if a drive breaks down, the data shall still be available on the other ones. Having a RAID also improves the overall performance as the input and output operations will be spread among a couple of drives. There are several kinds of RAID depending on 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 hard drives - whether it is 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 various RAID types may differ.
RAID in Cloud Hosting
The drives which we use for storage with our top-notch cloud Internet hosting platform are not the traditional HDDs, but quick solid-state drives (SSD). They work in RAID-Z - a special setup developed for the ZFS file system that we employ. Any content that you upload to the cloud hosting account will be kept on multiple disk drives and at least one of them will be employed as a parity disk. This is a specific drive where a further bit is added to any content copied on it. In the event that a disk in the RAID fails, it'll be replaced without any 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 other disks. This is done in order to ensure the integrity of the info and together with the real-time checksum validation which the ZFS file system executes on all drives, you won't ever need to worry about the loss of any information no matter what.