Mirror hard disk using dd.

[Livhu Tshisikule]

Hi,

I installed a second harddisk on my FBSD 5.2.1 box and then use dd if=/dev/ado 
of=/dev/ad1. I later removed my first disk so that I can test the second 
disk. After booting it goes to single user mode and then I used fsck -y 
command. I then mounted the /usr only to find that id did not copy everything 
from the first disk.

1. I want to make an exact copy of the first disk, how can I do that.
2. Later I want to copy what has changed to disk2 once a day. 

Regards
Livhu