Redundant Array of Independent Disks, or RAID, is a way of keeping content on a number of hard drives at the same time. A RAID might be software or hardware based on the hard drives that are used - physical or logical ones, yet what is common between them is the fact that they all function as just one single unit where information is saved. The biggest advantage of employing a RAID is redundancy because the data on all drives shall be exactly the same all the time, so even in the event that one of the drives fails for some reason, the information will still be available on the remaining drives. The general performance is also better since the reading and writing processes will be split between multiple drives, so a single one can't be overloaded. There're different kinds of RAIDs where the capabilities and fault tolerance could differ based on the exact setup - whether data is written on all drives in real time or it's written on one drive and then mirrored on another, what number of drives are used for the RAID, and many others.
RAID in Semi-dedicated Hosting
The RAID type which we employ for the cloud Internet hosting platform where your semi-dedicated hosting account shall be created is named RAID-Z. What is different about it is that at least one of the disks is used as a parity drive. Put simply, whenever any data is copied on this specific disk drive, one more bit is added to it and in case a malfunctioning disk is replaced, the info that will be duplicated on it is a mix of the data on the other disk drives in the RAID and that on the parity one. We do this to ensure that the data is intact. During this process, your sites will be functioning normally because RAID-Z enables an entire drive to fail without service disruptions and it simply works by using one of the remaining ones as the main production drive. Employing RAID-Z together with the ZFS file system that uses checksums to guarantee that no data can get silently corrupted on our servers, you won't ever need to worry about the integrity of your files.