Re: Debian + LVM + RAID1

[Ivan Glushkov <glushkov@mail.desy.de>]

Damon L. Chesser wrote:
> snip
>>
>> I taught I have to install the grub on the raid array, thus the grub
>> will put a copy of itself on the first partition on both hard drives,
>> used for the raid1, right?
>>   
> 
> Wrong  AFAIK.  You can do that IF you have a boot loader on the MBR
> pointing to grub.

Now I am confused. Isn't grub a boot loader? Why would I need another
boot loader pointing to grub? I want to put grub on the MBR of both hard
drives from which my raid1 array consist of.

BIOS does not read software raid and knows nothing
> about software raid.

Indeed, but I do not expect from the bios to read my raid array. I
merely want it to look for boot record in the MBR of one of the two hard
drives on which I have my raid arrays.

  Software raid does not come into play until the
> kernel via initrd is loaded.  Install to the MBR of the first HD of the
> array, then use grub to install into the MBR of the other members.

What I meant with the paragraph you are referring to is exactly that:
issuing:

grub-install /dev/md0

should install (as fas as I understand it) a copy of grub in each hdd
from which the raid1 consist of (note: the partitions from both hard
drives included in md0 are both 512 MB and starting from the beginning
of the hard drives).

If I
> am wrong, then it is news to me, but hey, I will learn new things!  See
> my old "howto" on Linux, grub and raid at damtek.com for the exact
> commands.  It is not pretty, but it will work.

I tried that. Thanks.

Basically the problem was easily solved. I had to tag both partitions to
be used for my /boot raid1 array as primary and bootable (stupid of me,
I know). But there is now another problem:

I see already the grub initial screen, but when I hit enter, I get the
following:

Booting 'Debian GNU/Linux, kernel 2.6.24-1-amd64'

root (hd5,0)
 Filesystem type unknown, partition type 0x7
kernel //vmlinuz-2.6.24-1-amd64 root=/dev/mapper/vg00-root ro linux26 quiet

Error 17: Cannot mount selected partition

Press any key to continue...

I suppose grub does not know anything about LVM and the partitions on
that. If I am right, I have to rebuild initrd, right? But how do I tell
it to enable the lvm?

	Cheers,
	Ivan