The term “backup” is widely used to describe the process of making copies of files. The aim of a backup is to enable users to restore the copied data stored, for example, on an external hard drive, in the Cloud or on a USB stick, in the event of data loss. Users should for this reason regularly check whether the backed-up data are complete, up to date and, above all, retrievable – it takes nothing more than a loose contact on the external hard drive for access to the backup to be blocked.