Reading the excellent book surveillance:// of Tristan Nitot, I have just learn the existence of a powerful Linux tool to perform backups, namely: rsync.
rsync is a command line utility and very easy to use. It is efficient because it only transfers files which are different between the source and destination directories. Assume that you want a backup of a source to a destination, then the command is just:
rsync -a <path-source> <path-destination>