grub on raid1 cannot mount filesystem

[Pavel Lisy]

Hello

I've found strange problem in new Fedora 15. I suppose it should work. 
It's maybe fdisk or grub problem.


Normaly I have this (working) multiboot solution on my home PC:

On first small (100MB) partition are grub1 files only with this config
(grub is installed to MBR): 

--- cut ---
title Fedora 15
   root (hd0,2)
   chainloader +1
title Fedora 14
   root (hd0,4)
   chainloader +1
title Ubuntu
   root (hd0,5)
   chainloader +1
--- cut ---

Grub of linux distributions is installed into their partitions


I want make the same on mirrored environment

2 HD in mirror (raid1):
	size	id	OS/SW		FS
1. part 200MB	fd 	grub		ext4
2. part 8GB	82	SWAP		swap
3. part 10 GB	fd	fedora 15	ext4
4. part extended
5. part 10 GB	fd	fedora 14	ext4
6. part 10 GB	fd	ubuntu		ext4
...
last part rest. of disk - LVM		

I've installed Fedora 15 on
/dev/md0 (/dev/sda1,/dev/sdb1)		/boot
/dev/md1 (/dev/sda3,/dev/sdb3)		/
grub was in MBR and everything worked.
THIS WORKS:
grub> root (hd0,0)
grub> setup (hd0)


When I want put grub of Fedora 15 to start of /dev/sda3 grub is
complaining:

THIS DOESN'T WORK:
grub> root (hd0,2)
grub> setup (hd0,2)
Error 17: cannot mount selected partition

Without mirror (raid1) it works. With raid1 it works only on first
partition. Can you explain me why? 

Thanks in advance

Pavel