[Osiris]

Nothing is more frustrating than to realize that some files of a backup are corrupted. This happens of course right at the time when you need the backup. One way to prevent this scenario from happening would be to use different locations for your backups, for example CDs, external hard drives and USB drives. Even though you store the backup in different places it is not guaranteed that the files on those devices are not corrupted. The probability that it will happen is simply reduced.
One way to check the backups for media integrity is to use a freeware called media checker. Media checker works with all media on devices that are currently connected to the computer it is running. It can scan folders or complete drives and really supports everything that you want to check for media integrity.
I contacted the author of Media Checker because it was not clear to me how media checker performed the check and decided whether a file was corrupted or not. The author answered me this way: “Media Checker considers the data to be safe when all the files in all subfolders of a selected media or folder can be read without any error from the beginning to the end. The program list all the files and attempt to read all of them byte by byte until the end.”
A way of using media checker would be to test the backups from time to time and react immediately when one check fails. This works best if you have two or even more backups of the same data of course.