Data corruption is the damage of info because of various hardware or software failures. The moment a file is damaged, it will no longer function properly, so an app will not start or shall give errors, a text file can be partially or completely unreadable, an archive file will be impossible to open and then unpack, etc. Silent data corruption is the process of data getting damaged without any acknowledgement by the system or an admin, that makes it a serious problem for web hosting servers as problems are more likely to happen on larger in size hard disks where vast volumes of info are located. When a drive is part of a RAID and the data on it is duplicated on other drives for redundancy, it's more than likely that the bad file will be treated as a healthy one and it'll be duplicated on all the drives, making the harm permanent. A lot of the file systems that operate on web servers nowadays often are unable to recognize corrupted files in real time or they need time-consuming system checks through which the server is not functioning.