Redundant Array of Independent Disks, or RAID, is a method of saving content on several hard disk drives concurrently. A RAID could be software or hardware based on the drives that are used - physical or logical ones, yet what is common between them is that they all function as one single unit where information is kept. The key advantage of using a RAID is redundancy because the info on all drives will be the same all the time, so even in case some drive fails for some reason, the info will still be available on the other drives. The general performance is enhanced as well because the reading and writing processes will be split between a number of drives, so a single one won't be overloaded. There're different sorts of RAIDs where the capabilities and fault tolerance may differ based on the particular setup - whether info is written on all drives in real time or it's written on one drive and after that mirrored on another, what number of drives are used for the RAID, etcetera.
RAID in Web Hosting
The hard drives that we employ for storage with our ground-breaking cloud Internet hosting platform are not the traditional HDDs, but high-speed solid-state drives (SSD). They work in RAID-Z - a special setup intended for the ZFS file system which we work with. All of the content that you upload to your web hosting account will be held on multiple drives and at least one of them shall be used as a parity disk. This is a specific drive where an extra bit is added to any content copied on it. In case a disk in the RAID fails, it will be changed without any service interruptions and the data will be recovered on the new drive by recalculating its bits thanks to the data on the parity disk along with that on the remaining disks. This is done so as to guarantee the integrity of the info and together with the real-time checksum validation that the ZFS file system performs on all drives, you will never need to worry about the loss of any data no matter what.
RAID in Semi-dedicated Servers
The info uploaded to any semi-dedicated server account is stored on SSD drives which work in RAID-Z. One of the drives in type of a setup is used for parity - whenever data is copied on it, an additional bit is added. If a disk happens to be defective, it will be removed from the RAID without disturbing the operation of the Internet sites because the data will load from the rest of the drives, and when a brand new drive is included, the info that will be copied on it will be a combination between the info on the parity disk and data stored on the other hard disks in the RAID. That is done so as to guarantee that the information which is being cloned is accurate, so as soon as the new drive is rebuilt, it could be incorporated into the RAID as a production one. This is an extra guarantee for the integrity of your data as the ZFS file system which runs on our cloud web hosting platform analyzes a unique checksum of all of the copies of the files on the different drives to be able to avoid any probability of silent data corruption.