software raid 1 and recovery

[Robin Becker]

I'm using software raid 1 on a 6.1 freebsd. This is a so called cold swap 
system, but I wonder how much it actually improves reliability. First off what 
should I be doing to detect error conditions and secondly what happens if the 
machine refuses to boot.

I set this system up using Dru Lavigne's recipe, but I don't really understand 
what happens if one of the drives starts to fail. I think there was some 
discussion about HD monitoring recently, but I can't seem to locate it.
-- 
Robin Becker