RAID, or Redundant Array of Independent Disks, is a technology for saving data on several hard drives that function together as one logical unit. The drives could be physical or logical i.e. in the aforementioned case a single drive is divided into different ones using virtualization software. Either way, identical information is saved on all drives and the basic benefit of using this type of a setup is that in case a drive stops working, the data shall still be available on the other ones. Employing a RAID also improves the performance as the input and output operations will be spread among a couple of drives. There are several types of RAID based on how many hard drives are used, whether writing is performed on all of the drives in real time or just on one, and how the data is synced 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. These factors suggest that the fault tolerance and the performance between the different RAID types could differ.