RAID, or Redundant Array of Independent Disks, is a technology of saving data on a number hard disk drives which work together as a single logical unit. The drives can be physical or logical i.e. in the aforementioned case a single drive is split into separate ones via virtualization software. In either case, exactly the same data is stored on all drives and the key advantage of employing such a setup is that in case a drive stops working, the data will remain available on the remaining ones. Employing a RAID also boosts the performance since the input and output operations will be spread among a number of drives. There are several types of RAID based on how many drives are used, whether writing is carried out on all drives in real time or just on a single one, and how the information is synchronized between the hard drives - whether it is written in blocks on one drive after another or it is mirrored from one on the others. All these factors indicate that the error tolerance and the performance between the various RAID types can vary.
RAID in Shared Hosting
The SSD drives that our cutting-edge cloud Internet hosting platform employs for storage operate in RAID-Z. This kind of RAID is designed to work with the ZFS file system that runs on the platform and it works by using the so-called parity disk - a special drive where information stored on the other drives is copied with an extra bit added to it. In case one of the disks fails, your sites shall continue working from the other ones and once we replace the bad one, the information which will be copied on it will be recovered from what is stored on the other drives as well as the information from the parity disk. This is performed so as to be able to recalculate the bits of each and every file properly and to validate the integrity of the data copied on the new drive. This is one more level of security for the content which you upload to your shared hosting account in addition to the ZFS file system that compares a unique digital fingerprint for each and every file on all the hard drives in real time.