Redundant Array of Independent Disks, or RAID, is a way of saving content on multiple hard disks simultaneously. A RAID might be software or hardware depending on the drives that are used - physical or logical ones, still what’s common between them is that they all function as a single unit where information is saved. The key advantage of employing a RAID is redundancy because the information on all drives will be identical all the time, so even in case one of the drives fails for some reason, the info will still be available on the other drives. The general performance is also enhanced as the reading and writing processes could be split between a number of drives, so a single one can't be overloaded. There're different sorts of RAIDs where the capabilities and fault tolerance could differ according to the exact setup - whether info is written on all of the drives real-time or it's written on a single drive and then mirrored on another, what amount of drives are used for the RAID, and so on.
RAID in Web Hosting
The SSD drives that our cutting-edge cloud hosting platform employs for storage operate in RAID-Z. This type of RAID is intended to work with the ZFS file system that runs on the platform and it works by using the so-called parity disk - a specific drive where information kept on the other drives is copied with an extra bit added to it. If one of the disks stops working, your sites will continue working from the other ones and once we replace the malfunctioning one, the info that will be duplicated on it will be recovered from what is stored on the remaining drives together with the information from the parity disk. This is done in order to be able to recalculate the elements of each file adequately and to validate the integrity of the data duplicated on the new drive. This is one more level of security for the content you upload to your web hosting account along with the ZFS file system which compares a unique digital fingerprint for each file on all the hard drives in real time.
RAID in Semi-dedicated Hosting
The RAID type that we use for the cloud web hosting platform where your semi-dedicated hosting account will be created is referred to as RAID-Z. What is different about it is that at least one of the disks is used as a parity drive. In simple terms, whenever any data is copied on this specific hard drive, one more bit is added to it and in case a problematic disk is replaced, the data that will be duplicated on it is a combination of the data on the remaining hard drives in the RAID and that on the parity one. We do this to guarantee that the data is intact. During this process, your sites will be working normally because RAID-Z enables a whole drive to fail without causing any service disruptions and it simply works by using one of the remaining ones as the main production drive. Using RAID-Z together with the ZFS file system that uses checksums to ensure that no data will get silently corrupted on our servers, you won't need to worry about the integrity of your files.
The SSD drives which we use on the machines where we set up virtual private servers operate in RAID to make sure that any content which you upload will be available and intact all of the time. At least 1 drive is used for parity - one bit of information is added to any data copied on it. If a main drive fails, it is changed and the information which will be cloned on it is calculated between the remaining drives and the parity one. This is done to ensure that the required info is copied and that no file is corrupted as the new drive will be used in the RAID afterwards. In addition, we use hard disks working in RAID on the backup servers, so if you add this upgrade to your VPS package, you'll use an even more reliable hosting service because your content will be available on multiple drives irrespective of any type of unforeseen hardware failure.