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 which hosting companies face because the larger a hard drive is and the more info is kept on it, the much more likely it is for data to become corrupted. There are various fail-safes, but often the info is damaged silently, so neither the file system, nor the admins detect anything. Because of this, a corrupted file will be treated as a standard one and if the hard disk is part of a RAID, that file will be copied on all other drives. Theoretically, this is done for redundancy, but in practice the damage will get worse. When a given file gets corrupted, it will be partially or entirely unreadable, therefore a text file will no longer be readable, an image file will present a random mix of colors if it opens at all and an archive will be impossible to unpack, so you risk sacrificing your content. Although the most well-known server file systems feature various checks, they quite often fail to find a problem early enough or require an extensive period of time to be able to check all files and the hosting server will not be functional in the meantime.