The process of files being corrupted due to some hardware or software failure is known as data corruption and this is one of the main problems that web hosting companies face since the larger a hard disk is and the more data is stored on it, the more likely it is for data to be corrupted. There're various fail-safes, yet often the information gets damaged silently, so neither the file system, nor the administrators detect anything. As a result, a corrupted file will be handled as a standard one and if the hard disk is part of a RAID, that file will be copied on all other drives. In theory, this is done for redundancy, but in reality the damage will be even worse. Once some 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 blend of colors if it opens at all and an archive will be impossible to unpack, so you risk losing your site content. Although the most widespread server file systems include various checks, they are likely to fail to detect a problem early enough or require a vast amount of time to check all files and the web hosting server will not be functional for the time being.