Grub in RHEL6 with RAID1?

[Tom H]

On Wed, Jan 5, 2011 at 2:28 PM, David C. Miller <millerdc at fusion.gat.com> wrote:
>
> Today I installed RHEL6 on system where I setup a RAID1
> for the / partition. There is no separate /boot. When it
> came to the screen that asked where the grub boot loader
> would be installed it selected /dev/sda. Obviously I want
> the boot loader installed on both drives in case sda fails
> the system will still boot. Under RHEL5 I would pick
> /dev/md0 and it would install a MBR on both drives.
> However, I tried that now and the system won't boot. So
> I booted the rescue disk and attempted to install grub
> manually. I have done this probably a dozen times in the
> past with no issues at all. I simply run grub. I typed in
> "root (hd0,0)" and hit return but this time it says
> filesystem type unknown. It is the default ext4 RHEL put
> on the Linux auto RAID partition. How do I properly load
> grub to the master boot record on both of these drives?
> How do you manually install grub to drive that has ext4 on it?

I had the same problem with F14 two days ago so there must be an
Anaconda-grub bug. :(

I did:
grub> device (hd0) /dev/sda
grub> root (hd0,0)
grub> setup (hd0)
...