Bug#531573: grub-pc: does not install onto partitionable mdadm mirror (raid1)

[Felix Zielcke]

Am Dienstag, den 02.06.2009, 18:00 +0400 schrieb Vladimir Stavrinov:
> Package: grub-pc
> Version: 1.96+20090523-1
> Severity: normal
> 
> 
> Try to install:
> 
> grub-install /dev/md_d0
> 
> and got the errors:
> 
> .............................................
> grub-probe: error: no mapping exists for `md0'
> Auto-detection of a filesystem module failed.
> Please specify the module with the option `--modules' explicitly.
> ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
> 
> Why it is referencing md0 if there is md_d0 only?
> --modules option don't help.

Because the GRUB device is still called md0. The actual /dev/ filename
doestn't matter.
That doestn't look right to install to /dev/md_d0
You should either use grub-install '(md0)' which installs it
automatically on all disks which are part of it or the old way with
grub-install /dev/sda etc.
But for RAID you need space for embeding which you maybe not have if you
want to setup it to md_d0.
That means you have to create a partition on all your RAID disks and
then setup the RAID over it, though you can still use a partionable RAID
array on it.
But there must be space between MBR and the first partition which is
always ~32 KiB with plain old msdos partition table.

Are you using maybe super block 1.x format instead of default 0.90?
grub2 doestn't support this.
And check that device.map contains all the disks your RAID is using.
-- 
Felix Zielcke