Design way to save and retrieve file for backup with file API

I tried to save a backup in the system context with fileaera='hub_backup'. However I discovered than I can't do that. The file API doesn't let me retrieve a "system context" fileinfo if the fileaera is not null.

get_file_info_system()

:

if (is_null($filearea)) {

            return new file_info_system($this);

        }

        //TODO: question files browsing

        return null;

I need to save a file in system context because the context cannot be course/user/module. These are the only available context.