You can connect to the FRITZ! with Samba too, because your USB-Disk is visible for Windows Clients too. You must only use root as username and your Fritz Password. My SME makes every night an Dump of the MySQL Database and an tar archive of all User Email Folders. Then he connect to Fritz USB-Disk and copy the Archive to the Disk. After that, he disconnects from FRITZ. I´m using my own Shell Script to di this. I´ve made seven scripts, for every Day once. The Crontab Manager start the scripts every night at 03:30. So I have seven Backup Archives on my FRITZ Disk of the last seven Days.
Kind Regards Igi