The process of files being damaged as a result of some hardware or software failure is known as data corruption and this is among the main problems which hosting companies face because the larger a hard drive is and the more data is kept on it, the much more likely it is for data to get corrupted. You can find a couple of fail-safes, still often the info is corrupted silently, so neither the file system, nor the admins detect anything. Consequently, a corrupted file will be handled as a standard one and if the hard disk is part of a RAID, that particular file will be copied on all other disk drives. In theory, this is for redundancy, but in reality the damage will be even worse. When some file gets damaged, it will be partially or fully unreadable, which means that a text file will no longer be readable, an image file will present a random blend of colors in case it opens at all and an archive will be impossible to unpack, and you risk sacrificing your website content. Although the most widespread server file systems feature various checks, they are likely to fail to detect some problem early enough or require a vast time period to check all of the files and the server will not be functional in the meantime.