RAID, or Redundant Array of Independent Disks, is a technology for storing data on multiple hard disk drives which operate together as a single logical unit. The drives can be physical or logical i.e. in the second case one drive is divided into different ones using virtualization software. In any case, identical data is saved on all of the drives and the basic benefit of using such a setup is that in case a drive stops working, the data will remain available on the other ones. Using a RAID also improves the overall performance since the input and output operations will be spread among a number of drives. There are several types of RAID depending on how many hard drives are used, whether writing is done on all drives in real time or just on a single one, and how the info is synchronized between the hard drives - whether it is recorded in blocks on one drive after another or all of it is mirrored from one on the others. All of these factors imply that the error tolerance and the performance between the various RAID types may differ.
RAID in Cloud Hosting
The SSD drives which our cutting-edge cloud Internet hosting platform employs for storage work in RAID-Z. This kind of RAID is created to work with the ZFS file system which runs on the platform and it works by using the so-called parity disk - a specific drive where information saved on the other drives is cloned with an additional bit added to it. In case one of the disks stops functioning, your websites will continue working from the other ones and as soon as we replace the faulty one, the data which will be duplicated on it will be recovered from what is stored on the remaining drives together with the information from the parity disk. This is done in order to be able to recalculate the bits of every single file correctly and to verify the integrity of the information cloned on the new drive. This is another level of security for the info which you upload to your cloud hosting account in addition to the ZFS file system which compares a unique digital fingerprint for every single file on all the disk drives in real time.
RAID in Semi-dedicated Servers
The information uploaded to any semi-dedicated server account is kept on SSD drives which work in RAID-Z. One of the drives in such a configuration is used for parity - any time data is cloned on it, an extra bit is added. In case a disk happens to be faulty, it will be removed from 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 data which will be copied on it will be a combination between the data on the parity disk and data saved on the other hard drives in the RAID. This is done in order to guarantee that the info which is being copied is accurate, so once the new drive is rebuilt, it can be integrated into the RAID as a production one. This is an additional guarantee for the integrity of your info as the ZFS file system which runs on our cloud Internet hosting platform compares a special checksum of all of the copies of the files on the separate drives so as to avoid any probability of silent data corruption.
RAID in VPS Servers
The SSD drives that we use on the physical machines where we create VPS servers operate in RAID to make sure that any content you upload will be available and intact all of the time. At least a single drive is used for parity - one bit of data is added to any data cloned on it. In case a main drive fails, it is replaced and the information 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 not a single file is corrupted because the new drive will be used in the RAID afterwards. In addition, we use hard disk drives operating in RAID on the backup servers, so in the event that you add this upgrade to your VPS plan, you shall use an even more reliable hosting service since your content will be available on multiple drives regardless of any kind of unpredicted hardware failure.