[CentOS] install on raid1

>Try something like this:
>
>Grub>device (hd0) /dev/sdb
>Grub>root (hd0,0)
>Grub>setup (hd0)

His syntax shows the installation from within a grub prompt which is right,
Yours looks more like what you use with grub-install. Regardless, his approach
is how my kickstart has been doing it for years with success...