RAID, which is short for Redundant Array of Independent Disks, is a software or hardware storage virtualization technology that enables a system to use a number of hard drives as one single logical unit. To put it differently, all of the drives are used as one and the information on all of them is identical. Such a setup has two huge advantages over using a single drive to save data - the first one is redundancy, so in the event that one drive breaks down, the info will be accessed through the remaining ones, and the second is better performance because the input/output, or reading/writing operations will be distributed among multiple drives. There're different RAID types depending on what amount of drives are employed, whether reading and writing are both handled from all drives concurrently, if data is written in blocks on one drive after another or is mirrored between drives in the same time, and so on. Determined by the particular setup, the error tolerance and the performance may differ.
RAID in Shared Web Hosting
The advanced cloud web hosting platform where all shared web hosting accounts are generated uses quick SSD drives as opposed to the traditional HDDs, and they work in RAID-Z. With this configuration, a number of hard drives work together and at least one of them is a dedicated parity disk. Put simply, when data is written on the other drives, it's duplicated on the parity one adding an extra bit. This is carried out for redundancy as even in case some drive fails or falls out of the RAID for some reason, the information can be rebuilt and verified thanks to the parity disk and the data stored on the other ones, so not a thing will be lost and there won't be any service disturbances. This is an additional level of protection for your info together with the state-of-the-art ZFS file system which uses checksums to make sure that all data on our servers is intact and is not silently corrupted.