The process of files being corrupted because of some hardware or software failure is referred to as data corruption and this is one of the main problems which hosting companies face as the larger a hard disk is and the more information is kept on it, the much more likely it is for data to be corrupted. You can find a couple of fail-safes, yet often the data is corrupted silently, so neither the file system, nor the administrators detect a thing. Because of this, a corrupted file will be treated as a regular one and if the hard disk is a part of a RAID, that particular file will be duplicated on all other disk drives. In theory, this is done for redundancy, but in reality the damage will get worse. The moment some file gets damaged, it will be partially or fully unreadable, therefore a text file will no longer be readable, an image file will present a random mix of colors in case it opens at all and an archive shall be impossible to unpack, and you risk sacrificing your content. Although the most popular server file systems have various checks, they are likely to fail to discover some problem early enough or require a long time period in order to check all files and the hosting server will not be operational for the time being.