Redundant Array of Independent Disks, or RAID, is a way of keeping content on several hard disk drives simultaneously. A RAID might be software or hardware depending on the drives that are used - physical or logical ones, however what is common between them is the fact that they all perform as a single unit where info is stored. The biggest advantage of employing a RAID is redundancy as the data on all the drives shall be identical all the time, so even in case some drive fails for whatever reason, the info will still be present on the rest of the drives. The overall performance will also improve as the reading and writing processes can be split between various drives, so a single one will never be overloaded. There're different sorts of RAIDs where the efficiency and fault tolerance may differ depending on the exact setup - whether your data is written on all of the drives in real time or it is written on a single drive and then mirrored on another, what amount of drives are used for the RAID, and so on.
RAID in Shared Web Hosting
The drives that we employ for storage with our ground-breaking cloud web hosting platform are not the standard HDDs, but extremely fast solid-state drives (SSD). They function in RAID-Z - a special setup created for the ZFS file system which we work with. Any content that you add to the shared web hosting account will be kept on multiple hard disks and at least 1 will be employed 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 changed with no 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 remaining disks. This is done to guarantee the integrity of the information and together with the real-time checksum validation which the ZFS file system runs on all drives, you'll never need to concern yourself with losing any info no matter what.
RAID in Semi-dedicated Hosting
The RAID type that we employ for the cloud Internet hosting platform where your semi-dedicated hosting account shall be created is referred to as RAID-Z. What is different about it is that at least one of the disks is employed as a parity drive. Simply put, whenever any data is duplicated on this special drive, one more bit is included to it and if a problematic disk is replaced, the data that will be duplicated on it is a mix of the data on the remaining hard disks in the RAID and that on the parity one. It's done this way to guarantee that the data is intact. During this process, your sites will be working normally as RAID-Z allows for a whole drive to fail without service disruptions and it simply uses one of the other ones as the main production drive. Employing RAID-Z together with the ZFS file system that uses checksums to warrant that no data will get silently corrupted on our servers, you will never have to worry about the integrity of your files.