The process of files being corrupted as a consequence of some hardware or software failure is called data corruption and this is among the main problems that Internet hosting companies face since the larger a hard disk drive is and the more information is placed on it, the much more likely it is for data to get corrupted. You'll find different fail-safes, yet often the information becomes damaged silently, so neither the file system, nor the administrators notice anything. Because of this, a bad file will be treated as a good one and if the hard disk is part of a RAID, that particular file will be copied on all other disk drives. Theoretically, this is for redundancy, but in reality the damage will get even worse. Once a file gets damaged, it will be partially or completely unreadable, therefore a text file will no longer be readable, an image file will present a random combination of colors if it opens at all and an archive will be impossible to unpack, and you risk losing your content. Although the most popular server file systems feature various checks, they are likely to fail to find a problem early enough or require a vast time period in order to check all files and the hosting server will not be operational in the meantime.