The process of files being damaged as a consequence of some hardware or software failure is called data corruption and this is one of the main problems that web hosting companies face as the larger a hard drive is and the more data is stored on it, the much more likely it is for data to get corrupted. There are a couple of fail-safes, still often the data becomes damaged silently, so neither the particular file system, nor the administrators see anything. Thus, a corrupted file will be treated as a good one and if the hard disk is part of a RAID, that file will be duplicated on all other drives. In theory, this is for redundancy, but in practice the damage will be 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 show a random blend of colors in case it opens at all and an archive shall be impossible to unpack, so you risk sacrificing your site content. Although the most well-known server file systems include various checks, they often fail to identify a problem early enough or require a vast amount of time to check all files and the server will not be operational in the meantime.