RAID, or Redundant Array of Independent Disks, is a technology of saving data on a number hard disks which work together as a single logical unit. The drives could be physical or logical i.e. in the latter case a single drive is split into different ones through virtualization software. In any case, the very same information is kept on all of the drives and the main benefit of using such a setup is that in the event that a drive breaks down, the data will still be available on the other ones. Having a RAID also enhances the overall performance since the input and output operations will be spread among a couple of drives. There are several types of RAID depending on how many hard disks are used, whether writing is done on all of the drives in real time or just on one, and how the information is synchronized between the hard drives - whether it's written in blocks on one drive after another or it is mirrored from one on the others. All these factors show that the fault tolerance as well as the performance between the various RAID types may vary.
RAID in Hosting
Our state-of-the-art cloud web hosting platform where all hosting accounts are made employs quick SSD drives rather than the classic HDDs, and they operate in RAID-Z. With this configuration, a number of hard drives work together and at least one is a dedicated parity disk. Simply put, when data is written on the rest of the drives, it's cloned on the parity one adding an extra bit. This is performed for redundancy as even in case a drive fails or falls out of the RAID for whatever reason, the information can be rebuilt and verified thanks to the parity disk and the data stored on the other ones, so practically nothing will be lost and there won't be any service disorders. This is another level of protection for your data along with the top-notch ZFS file system which uses checksums to guarantee that all of the data on our servers is undamaged and is not silently corrupted.
RAID in Semi-dedicated Hosting
The data uploaded to any semi-dedicated hosting account is saved on SSD drives that operate in RAID-Z. One of the drives in type of a configuration is used for parity - any time data is cloned on it, an additional bit is added. In case a disk turns out to be faulty, it will be taken out of the RAID without disturbing the operation of the sites since the data will load from the remaining drives, and when a new drive is included, the info that will be copied on it will be a blend between the info on the parity disk and data kept on the other hard drives in the RAID. This is done so as to guarantee that the info which is being copied is accurate, so the moment the new drive is rebuilt, it can be integrated into the RAID as a production one. This is an extra warranty for the integrity of your info because the ZFS file system which runs on our cloud web hosting platform compares a unique checksum of all the copies of the files on the separate drives to be able to avoid any probability of silent data corruption.
The SSD drives which we use on the machines where we create virtual private servers work in RAID to ensure that any content that you upload will be available and intact at all times. At least one drive is employed for parity - one bit of information is added to any data copied on it. In case a main drive breaks down, it is replaced and the data which will be copied on it is calculated between the other drives and the parity one. That’s done to ensure that the needed data is copied and that no file is corrupted because the new drive will be incorporated into the RAID afterwards. In addition, we use hard disks working in RAID on the backup servers, so if you add this upgrade to your VPS package, you shall use an even more reliable hosting service since your content will be available on multiple drives irrespective of any kind of sudden hardware failure.