Using a USB external hard disk for backups with Linux

"In this article, I show how I set up a recently purchased USB external hard disk drive as a backup drive for my Linux desktop PC. I'll delete the default FAT32 partition, create a new partition, make a reiserfs filesystem, and show how to use rsync to backup your important data."

http://www.basicallytech.com/blog/index.php?/archives/73-Using-a-USB-external-hard-disk-for-backups-with-Linux.html

rsync Tips & Tricks

"Tips on using the rsync command. rsync performs incremental filesystem transfers, allowing filesystem duplication or snap shotting. Alternatives to rsync on Unix systems include cp -r, pipes between tar commands, or unison."

http://sial.org/howto/rsync/