I just bought a 1.5T HDD and a disk enclosure. I connected this disk to my laptop via the provided USB cable. I then used the following command:
rsync -r -t -v --progress --delete -c -l -z / /media/C4E41A11E41A0678/Moonface_BKP/
I ran this for a long (long long) time when i noticed that what had been backed up to the HDD began to be backed up. In other words, when i ran the command, it created a /media directory and a C4... directory below that and kept recursively backing up this directory (since, I suppose, I was backing up the hard drive itself, too).
So...what's the proper way to use rsync?