Rsync makes it very easy to do speedy professional backups copying only the differences between two specified files or directories.
Here's a quick example of backing up a directory recursively - in archive mode (-a) and verbally (-v) showing progress --progress in human readable format (-h) and deleting deleted files on the destiny location --delete (careful with that!!).
rsync -avh --delete --progress /var/www /mnt/bigdrive/