How do I make a new disk bootable?

[Pierre Abbat <phma@xxxxxxxxxxxx>]

Darner has three disks: ad0 is the old IDE disk, ad4 is the SATA disk which 
has everything that was on ad0, and ad6 is the other SATA disk. It uses ad0 
only for booting; I'd like to get rid of it. So I typed:
# boot0cfg -B /dev/ad4
(actually the /dev/serno equivalent), turned it off, disconnected the power 
from ad0, and rebooted. It gave an F1 menu. I hit F1, and it beeped.

I'm guessing that slice 1, which is active, needs something written to sector 
0 to make it bootable. How do I do this?

Pierre
-- 
loi mintu se ckaji danlu cu jmaji