RAID, or Redundant Array of Independent Disks, is a technology for storing data on a number hard disk drives that function together as one logical unit. The drives can be physical or logical i.e. in the second case one drive is split into separate ones via virtualization software. In any case, the same info is kept on all drives and the key benefit of employing such a setup is that if a drive fails, the data shall 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 few drives. There are several types of RAID depending on how many drives are used, whether writing is done on all 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 imply that the fault tolerance and the performance between the different RAID types may vary.
RAID in Shared Website Hosting
The hard disks that we use for storage with our ground-breaking cloud hosting platform are not the traditional HDDs, but high-speed solid-state drives (SSD). They operate in RAID-Z - a special setup developed for the ZFS file system which we employ. All the content that you add to the shared website hosting account will be held on multiple hard drives and at least 1 shall be used as a parity disk. This is a special drive where an additional bit is included to any content copied on it. In the event that a disk in the RAID stops working, it'll be replaced without service interruptions and the information will be rebuilt on the new drive by recalculating its bits using the data on the parity disk plus that on the other disks. This is done to ensure the integrity of the info and along with the real-time checksum authentication that the ZFS file system performs on all drives, you will never need to be concerned about losing any data no matter what.
RAID in Semi-dedicated Hosting
The information uploaded to any semi-dedicated hosting account is kept on SSD drives which operate in RAID-Z. One of the drives in this kind of a setup is used for parity - every time data is cloned on it, an extra bit is added. In case a disk turns out to be problematic, it will be taken out of the RAID without interrupting the functioning of the websites as the data will load from the other drives, and when a new drive is included, the data that will be duplicated on it will be a combination between the data on the parity disk and data saved on the other hard disks in the RAID. That is done to ensure that the information that is being cloned is correct, so once the new drive is rebuilt, it can be included in the RAID as a production one. This is one more guarantee for the integrity of your data since the ZFS file system that runs on our cloud hosting platform analyzes a special checksum of all copies of the files on the separate drives to avoid any chance of silent data corruption.
All virtual private server accounts which our company offers are generated on physical servers that take advantage of SSD drives operating in RAID. At least 1 drive is intended for parity - one extra bit is included in the information copied on it and in case a main disk stops working, this bit makes it much easier to recalculate the bits of the files on the damaged hard disk so that the right data is restored on the new drive added to the RAID. In the mean time, your Internet sites will remain online since all the data will still load from at least one other drive. In case you add regular backups to your VPS package, a copy of your info will be saved on standard hard disks which also operate in RAID as we want to make sure that any kind of site content you add will be safe and sound all the time. Working with multiple drives in RAID for all of the main and backup servers permits us to offer fast and reliable hosting service.