The process of files getting corrupted resulting from some hardware or software failure is known as data corruption and this is one of the main problems which hosting companies face because the larger a hard disk is and the more info is filed on it, the more likely it is for data to get corrupted. You'll find a couple of fail-safes, still often the info becomes damaged silently, so neither the file system, nor the admins detect a thing. As a result, a bad file will be handled as a regular one and if the hard drive is a part of a RAID, that particular file will be copied on all other disk drives. In principle, this is done for redundancy, but in reality the damage will get even worse. Once a file gets corrupted, it will be partially or completely unreadable, therefore a text file will not be readable, an image file will present a random mix of colors if it opens at all and an archive shall be impossible to unpack, and you risk losing your content. Although the most widespread server file systems feature various checks, they frequently fail to find a problem early enough or require a long time period to check all of the files and the server will not be functional in the meantime.