use dd to copy 1 hd to another?
My main hd is 500 gb. I have an usb-hd that also is 500 gb.
I want to copy the main hd to the usb-hd so if
the main hd should crash i can boot from the backup hd.
I think dd is the command to use. I have checked the man-page but there
are so many options.. Anyone knows how to use dd to do this?