RAID, which is short for Redundant Array of Independent Disks, is a software or hardware storage virtualization technology that makes it possible for a system to employ a number of hard drives as a single logical unit. In other words, all drives are used as one and the information on all of them is identical. Such a setup has 2 key advantages over using just a single drive to store data - the first is redundancy, so in the event that one drive breaks down, the information will be accessed through the others, and the second one is improved performance since the input/output, or reading/writing operations will be distributed among multiple drives. There're different RAID types in accordance with the number of drives are used, whether reading and writing are both performed from all of the drives at the same time, whether data is written in blocks on one drive after another or is mirrored between drives in the same time, and so on. Depending on the exact setup, the error tolerance and the performance could differ.
RAID in Shared Hosting
The hard disks that we employ for storage with our revolutionary cloud hosting platform are not the standard HDDs, but high-speed solid-state drives (SSD). They function in RAID-Z - a special setup created for the ZFS file system that we work with. Any content that you upload to the shared hosting account will be held on multiple disk drives and at least one of them shall be employed as a parity disk. This is a special drive where an additional bit is included to any content copied on it. In the event that a disk in the RAID stops working, it'll be changed without 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 other disks. This is done to guarantee the integrity of the info and along with the real-time checksum validation which the ZFS file system executes on all drives, you will never need to concern yourself with the loss of any info no matter what.