RAID, or Redundant Array of Independent Disks, is a technology for storing data on multiple hard drives which operate together as a single logical unit. The drives can be physical or logical i.e. in the latter case one single drive is divided into individual ones via virtualization software. Either way, the very same info is saved on all of the drives and the basic benefit of using this type of a setup is that in case a drive breaks down, the data shall still be available on the other ones. Employing a RAID also boosts the performance since the input and output operations will be spread among a couple of drives. There are several types of RAID based on how many drives are used, whether writing is performed on all the drives in real time or just on a single one, and how the data is synchronized between the drives - whether it's written in blocks on one drive after another or all of it is mirrored from one on the others. All of these factors suggest that the error tolerance and the performance between the various RAID types may differ.
RAID in Cloud Hosting
The hard drives that we use for storage with our revolutionary cloud web hosting platform are not the classic HDDs, but fast solid-state drives (SSD). They work in RAID-Z - a special setup created for the ZFS file system which we use. Any content that you upload to your cloud hosting account will be held on multiple hard disks and at least 1 will be used as a parity disk. This is a specific drive where an additional bit is added to any content copied on it. In case a disk in the RAID stops functioning, it will be changed without service disruptions 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 other disks. This is done so as to guarantee the integrity of the information and together with the real-time checksum verification that the ZFS file system performs on all drives, you'll never need to be concerned about the loss of any data no matter what.