I searched around, but maybe this is just too simple

I am looking for an easy, convenient solution that can do an incremental backup all files in my Samba/Greyhole shares to an external harddisk (like the WHS v1 server backup).
Ideally, no encryption, no fuzz, so that I could attach it to any PC in case something went wrong.
Backup can be started on demand (or when the external HDD is turned on/ detected, if that is easy enough).
THX!
Nico