[CentOS] 4 X 500 gb drives - best software raid config for a backup server?

> Would it be best to raid 1 two drives each and LVM them together?
>
> My next question would be about how to do this as I have never done a  
> linux software raid.
>   

I would do it this way if they are not system disks:

Eg:
sdc + sdd = md0 (raid 1)
sde + sdf = md1 (raid 1)
md0 + md1 = md2 (raid 0)


Use md2 as a physical volume