RAID, which is short for Redundant Array of Independent Disks, is a software or hardware storage virtualization technology which allows a system to use a number of hard drives as one single logical unit. In other words, all of the drives are used as one and the info on all of them is identical. This kind of a setup has 2 major advantages over using just a single drive to store data - the first is redundancy, so if one drive stops working, the data 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 a number of drives. There're different RAID types based on the number of drives are used, whether reading and writing are both performed from all 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, etcetera. According to the particular setup, the error tolerance and the performance may differ.
RAID in Web Hosting
The SSD drives that our cutting-edge cloud Internet hosting platform uses for storage function in RAID-Z. This kind of RAID is designed to work with the ZFS file system which runs on the platform and it takes advantage of the so-called parity disk - a special drive where data kept on the other drives is duplicated with an extra bit added to it. In the event that one of the disks stops functioning, your Internet sites will continue working from the other ones and after we replace the faulty one, the data which will be copied on it will be recovered from what is stored on the other drives along with the info from the parity disk. This is done in order to be able to recalculate the bits of every file properly and to confirm the integrity of the data copied on the new drive. This is one more level of security for the information which you upload to your web hosting account along with the ZFS file system that analyzes a special digital fingerprint for every single file on all of the drives in real time.
RAID in Semi-dedicated Hosting
The data uploaded to any semi-dedicated hosting account is kept on SSD drives which work in RAID-Z. One of the drives in this kind of a configuration is used for parity - every time data is copied on it, an extra bit is added. If a disk turns out to be defective, it will be taken out of the RAID without disturbing the operation of the sites as the data will load from the rest of the drives, and when a new drive is included, the data that will be copied on it will be a combination between the info on the parity disk and data stored on the other hard drives in the RAID. That is done in order to guarantee that the information that is being copied is accurate, so the moment the new drive is rebuilt, it could be incorporated into the RAID as a production one. This is an additional warranty for the integrity of your data as the ZFS file system that runs on our cloud hosting platform compares a special checksum of all copies of the files on the various drives to avoid any chance of silent data corruption.