The process of files getting damaged due to some hardware or software failure is known as data corruption and this is among the main problems which hosting companies face because the larger a hard drive is and the more information is filed on it, the more likely it is for data to be corrupted. You can find several fail-safes, yet often the information gets corrupted silently, so neither the file system, nor the administrators notice anything. Thus, a damaged file will be handled as a good one and if the HDD is part of a RAID, that particular file will be copied on all other drives. In principle, this is done for redundancy, but in reality the damage will get worse. The moment a given file gets damaged, it will be partly or entirely unreadable, which means that 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 shall be impossible to unpack, so you risk sacrificing your website content. Although the most widespread server file systems include various checks, they are likely to fail to find a problem early enough or require a vast time period to check all the files and the server will not be functional in the meantime.