Thank you for your replies.
I looked for compatible nas but I haven't found anything suitable.
I'm thinking about another solution: what do you think if I install a backup server (windows based with one backup software installed), then I connect this server to the company network on one lan port, and the nas on another lan port creating a sort of "private network" between this server and the nas. The autoloader will connect to this server using scsi (it is connected in this way at the moment).
Then the backup server could copy data from company servers (exch, sql, fileserver, ecc) to the nas by night, and then copy data from nas to the tape library during the day, without accessing the company network because data don't exit from the backup server.
I hope you can understand. Do you think it could be a nice solution?