Hello,
On what level do you want to perform a backup? Personal (from one computer to for example an external disk), professional level (multiple computers / servers connecting to a centralized backup server with tape / disk / ...), or something in between? You could have a look at
Amanda,
Zmanda,
Bacula and many others for an enterprise level solution. On a personal level you can use tools like rsync,
BackupPC, ... Look at Google for more available solutions.
Kind regards,
Eric