RAID, which is an acronym of Redundant Array of Independent Disks, is a software or hardware storage virtualization technology which enables a system to use a number of hard drives as a single logical unit. Put simply, all the drives are used as one and the info on all of them is identical. Such a configuration has two key advantages over using just a single drive to keep data - the first one is redundancy, so in the event that one drive breaks down, the information will be accessible from the remaining ones, and the second one is improved performance because the input/output, or reading/writing operations will be distributed among multiple drives. There are different RAID types based on how many drives are used, if reading and writing are both done from all the drives concurrently, if data is written in blocks on one drive after another or is mirrored between drives in the same time, and many others. Depending on the particular setup, the error tolerance and the performance could differ.
RAID in Web Hosting
The disk drives that we use for storage with our revolutionary cloud hosting platform are not the classic HDDs, but extremely fast solid-state drives (SSD). They work in RAID-Z - a special setup designed for the ZFS file system that we work with. All the content that you add to your web hosting account will be stored on multiple drives and at least 1 will be used as a parity disk. This is a special drive where an additional bit is included to any content copied on it. If a disk in the RAID fails, it will be replaced with no service interruptions and the information will be rebuilt on the new drive by recalculating its bits thanks to the data on the parity disk along with that on the other disks. This is done in order to ensure the integrity of the info and along with the real-time checksum verification that the ZFS file system runs on all drives, you will never need to concern yourself with losing any info no matter what.