RAID, or Redundant Array of Independent Disks, is a technology of keeping data on multiple hard disks that function together as a single logical unit. The drives could be physical or logical i.e. in the second case one drive is divided into independent ones through virtualization software. In any case, the very same info is saved on all drives and the basic advantage of employing such a setup is that if a drive breaks down, the data will still be available on the other ones. Employing a RAID also improves the performance since the input and output operations will be spread among a couple of drives. There are several kinds of RAID depending on how many drives are used, whether writing is performed on all drives in real time or just on a single one, and how the data is synced 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 mean that the error tolerance as well as the performance between the different RAID types may vary.
RAID in Website Hosting
The state-of-the-art cloud web hosting platform where all website hosting accounts are made employs fast SSD drives as an alternative to the standard HDDs, and they function in RAID-Z. With this setup, several hard drives operate together and at least one is a dedicated parity disk. Simply put, when data is written on the remaining drives, it's duplicated on the parity one adding an extra bit. This is done for redundancy as even in case a drive fails or falls out of the RAID for some reason, the info can be rebuilt and verified thanks to the parity disk and the data saved on the other ones, therefore not a thing will be lost and there will not be any service disturbances. This is one more level of protection for your data in addition to the top-notch ZFS file system that uses checksums to guarantee that all the data on our servers is undamaged and is not silently corrupted.