Redundant Array of Independent Disks, or RAID, is a way of saving content on several hard disk drives at the same time. A RAID can be software or hardware based on the hard drives which are used - physical or logical ones, yet what is common between them is that they all operate as just one single unit where data is saved. The main advantage of using a RAID is redundancy since the data on all drives is identical all of the time, so even in the event that some drive fails for whatever reason, the info will still be available on the rest of the drives. The general performance is enhanced as well since the reading and writing processes could be split between multiple drives, so a single one will never be overloaded. There're different sorts of RAIDs where the performance and fault tolerance could differ according to the particular setup - whether info is written on all the drives in real time or it is written on one drive and afterwards mirrored on another, the number of drives are used for the RAID, and many others.
RAID in Shared Hosting
The state-of-the-art cloud hosting platform where all shared hosting accounts are created uses fast SSD drives rather than the classic HDDs, and they work in RAID-Z. With this setup, a number of hard disks function together and at least one is a dedicated parity disk. Simply put, when data is written on the rest of the drives, it is cloned on the parity one adding an extra bit. This is performed for redundancy as even if a drive fails or falls out of the RAID for some reason, the data can be rebuilt and verified thanks to the parity disk and the data recorded on the other ones, so not a single thing will be lost and there will not be any service disorders. This is another level of protection for your information along with the advanced ZFS file system that uses checksums to make sure that all data on our servers is intact and is not silently corrupted.
RAID in Semi-dedicated Hosting
The info uploaded to any semi-dedicated hosting account is stored on SSD drives which work in RAID-Z. One of the drives in this kind of a setup is used for parity - whenever data is cloned on it, an additional bit is added. In case a disk turns out to be faulty, it will be taken out of the RAID without interrupting the work of the Internet sites since the data will load from the remaining drives, and when a brand new drive is included, the data that will be cloned on it will be a combination between the info on the parity disk and data kept on the other hard disks in the RAID. That is done to ensure that the info that is being cloned is accurate, so once the new drive is rebuilt, it can be included in the RAID as a production one. This is an additional warranty for the integrity of your info as the ZFS file system which runs on our cloud Internet hosting platform analyzes a special checksum of all copies of your files on the various drives to avoid any possibility of silent data corruption.