The process of files being corrupted caused by some hardware or software failure is referred to as data corruption and this is one of the main problems that hosting companies face because the larger a hard disk is and the more information is stored on it, the more likely it is for data to be corrupted. There're various fail-safes, still often the information becomes corrupted silently, so neither the particular file system, nor the administrators see anything. Consequently, a corrupted file will be handled as a good one and if the hard disk drive is part of a RAID, that particular file will be copied on all other disk drives. In principle, this is for redundancy, but in reality the damage will be even worse. When some file gets damaged, it will be partly or fully unreadable, therefore a text file will not be readable, an image file will present a random combination of colors in case it opens at all and an archive will be impossible to unpack, and you risk sacrificing your content. Although the most widespread server file systems include various checks, they quite often fail to detect a problem early enough or require a long period of time to check all of the files and the server will not be operational in the meantime.