RAID, which stands short for Redundant Array of Independent Disks, is a software or hardware storage virtualization technology that enables a system to take advantage of several hard drives as one single logical unit. Put simply, all the drives are used as one and the info on all of them is the same. Such a configuration has 2 huge advantages over using just a single drive to store data - the first one is redundancy, so if one drive stops working, the data will be accessible from the others, and the second is better performance because the input/output, or reading/writing operations will be spread among several drives. There are different RAID types based on what number of drives are employed, whether reading and writing are both done 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. Based on the exact setup, the error tolerance and the performance may differ.
RAID in Shared Hosting
Any content that you upload to your new shared hosting account will be held on quick SSD drives which work in RAID-Z. This configuration is built to work with the ZFS file system which runs on our cloud hosting platform and it adds another level of protection for your content on top of the real-time checksum validation which ZFS uses to guarantee the integrity of the data. With RAID-Z, the data is saved on a couple of disks and at least one is a parity disk - whenever data is written on it, an additional bit is added, so if any drive stops working for whatever reason, the stability of the data can be verified by recalculating its bits based on what is kept on the production hard drives and on the parity one. With RAID-Z, the functioning of our system will not be interrupted and it'll continue operating effectively until the malfunctioning drive is changed and the info is synchronized on it.
RAID in Semi-dedicated Servers
The RAID type that we use for the cloud hosting platform where your semi-dedicated server account shall be created is called 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 kind of data is copied on this particular drive, one more bit is included to it and in case a problematic disk is changed, the data that will be copied on it is a mix of the data on the remaining disk drives in the RAID and that on the parity one. This is done to make sure that the info is intact. During this process, your sites will be up and running normally because RAID-Z enables a whole drive to fail without any service disruptions and it simply uses one of the other ones as the main production drive. Using RAID-Z together with the ZFS file system which uses checksums to guarantee that no data can get silently corrupted on our servers, you won't ever have to worry about the integrity of your files.
RAID in VPS Servers
The SSD drives that we use on the physical machines where we generate VPS servers work in RAID to make sure that any content which you upload will be available and intact all of the time. At least one drive is used for parity - one bit of information is added to any data cloned on it. In case a main drive fails, it is changed and the information that will be duplicated on it is calculated between the rest of the drives and the parity one. That’s done to ensure that the correct data is copied and that no file is corrupted because the new drive will be used in the RAID afterwards. Also, we use hard disks working in RAID on the backup servers, so in case you add this upgrade to your VPS plan, you'll use an even more reliable web hosting service because your content will be available on multiple drives irrespective of any kind of unpredicted hardware malfunction.