A data backup system is provided for backing up data files from a data source and for securing those data files against accidental modification or deletion. The system comprises storage and a data protection component that includes an application programming interface defining a command set. The system can also comprise a backup application that is configured to use the commands of the command set. The data protection component allows applications that use the commands of the command set, such as the backup application, to access the storage of the system. The data protection component prevents operating systems and applications that do not use the commands of the command set from accessing the storage. The data protection function of the data protection component can optionally be disabled to allow open access to the storage.