RAID, or Redundant Array of Independent Disks, is a technology of keeping data on a number hard disks that work together as a single logical unit. The drives could be physical or logical i.e. in the aforementioned case a single drive is divided into separate ones via virtualization software. In either case, identical data is kept on all drives and the basic advantage of using such a setup is that in the event that a drive fails, the data will still be available on the remaining ones. Using a RAID also boosts the overall performance because the input and output operations will be spread among a few drives. There are several types of RAID dependant upon how many hard disks are used, whether writing is carried out 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 mean that the error tolerance as well as the performance between the various RAID types could differ.
RAID in Hosting
All the content that you upload to your new hosting account will be stored on fast SSD drives that work in RAID-Z. This setup is built to work with the ZFS file system which runs on our cloud hosting platform and it adds an additional level of protection for your site content on top of the real-time checksum verification which ZFS uses to ensure the integrity of the data. With RAID-Z, the data is saved on several disks and at least one is a parity disk - whenever data is written on it, an extra bit is added, so in case any drive fails for whatever reason, the integrity of the info can be verified by recalculating its bits based on what is saved on the production disks and on the parity one. With RAID-Z, the operation of our system will not be interrupted and it'll continue operating smoothly until the problematic drive is replaced and the data is synchronized on it.