RAID, or Redundant Array of Independent Disks, is a technology for keeping data on several hard disk drives that function together as one single logical unit. The drives can be physical or logical i.e. in the second case one drive is split into different ones using virtualization software. In any case, the very same information is saved on all the drives and the basic advantage of using this kind of a setup is that in the event that a drive stops working, the data will remain available on the remaining ones. Having a RAID also improves the overall performance because the input and output operations will be spread among a couple of drives. There are several types of RAID based on how many hard drives are used, whether writing is performed on all the drives in real time or just on a single one, and how the info is synchronized between the hard drives - whether it's recorded in blocks on one drive after another or all of it is mirrored from one on the others. These factors indicate that the fault tolerance and the performance between the different RAID types can vary.
RAID in Hosting
The SSD drives that our cutting-edge cloud hosting platform uses for storage work in RAID-Z. This kind of RAID is designed to work with the ZFS file system which runs on the platform and it takes advantage of the so-called parity disk - a special drive where info kept on the other drives is cloned with an additional bit added to it. In case one of the disks fails, your Internet sites shall continue working from the other ones and after we replace the malfunctioning one, the information which will be copied on it will be recovered from what is stored on the rest of the drives along with the info from the parity disk. This is done in order to be able to recalculate the elements of each file correctly and to validate the integrity of the data duplicated on the new drive. This is one more level of security for the info that you upload to your hosting account together with the ZFS file system which compares a unique digital fingerprint for each file on all the hard drives in real time.