10.04 desktop RAID 10 install?

[Goh Lip]

On 06/24/2010 01:21 PM, Tom H wrote:
> On Wed, Jun 23, 2010 at 10:20 PM, Goh Lip<g.lip at gmx.com>  wrote:
>> On 06/24/2010 09:46 AM, Alan McKay wrote:
>>>> Make sure your boot is non-mdadm'd or RAID1.
>>>
>>> yeah, I'd read that somewhere.
>>>
>>> So I ahve it working.  I have a 512M RAID1 layed across all 4 disks
>>> (though looks like mdadm only took the first 3 of them but I don't
>>> care).  Then 2G swap part on each of the 4 disks.  Then the rest of
>>> the 1T goes to a RAID10
>>>
>>> It is running and working great.  The only thing I am having trouble
>>> with is grub.   It works mind you.  But one of the articles I'd read
>>> said basically when doing the RAID1 approach for /boot, to make sure
>>> the boot loader is installed on all of the disks in the RAID1.  And
>>> damned if I know how to do that.  Been reading man pages and checking
>>> google and still nothing.
>>
>> To install grub to other disks...
>> grub-install --root-directory=/media/disk_other/ /dev/sdx
>>
>> Note it will *not* create grub.cfg file to the other disk.
>
> It's not quite as simple as that.
>
> I had said on the list some time ago that grub1 couldn't boot from an
> mdadm'd /boot and that I'd never worked anywhere that did that.
> Christopher C corrected me and he was right.
>
> Out of curiosity, I checked the RHEL documentation since this is what
> we run and I found:
> http://www.redhat.com/docs/manuals/enterprise/RHEL-5-manual/Installation_Guide-en-US/s1-grub-installing.html
> http://www.redhat.com/docs/en-US/Red_Hat_Enterprise_Linux/5.5/html/Installation_Guide/s1-grub-installing.html
>
> The problem is that you have to trick grub in order to ensure that you
> can boot from a degraded raid by installing grub onto sda and sdb with
> both being (hd0).
>
> For grub1, you would run (assuming /boot is on sdX1):
>
> # grub
> grub>  device (hd0) /dev/sda
> grub>  root (hd0,0)
> grub>  setup (hd0)
> grub>  quit
>
> and
>
> # grub
> grub>  device (hd0) /dev/sdb
> grub>  root (hd0,0)
> grub>  setup (hd0)
> grub>  quit
>
> For grub2, the only equivalent procedure that I can think of is to
> back up device.map, set (hd0) as /dev/sda in device.map, run
> grub-install /dev/sda, set (hd0) as /dev/sdb in device.map, run
> grub-install /dev/sdb.
>

Okay,right. I not worked with raid or lvm and I too have read somewhere 
these may pose some problems with grub. The solution I read is to 
disable lvm or raid, set grub in all disks and then enable these back, 
or like you said somewhere, have the /boot in a non-raid area. But, like 
I said, I've not used them.

Alan appears to know what he needs to do with raid and if he just want a 
simple "How to install grub to other disks", well then...

If this can be resolved with grub-legacy by your message on devicemap 
above, hope you can sort this out with grub2 too.

Can this link help?

http://grub.enbug.org/FranklinPiat/grub-mkdevicemap.manpage

sudo grub-mkdevicemap --devicemap=FILE

Good luck - Goh Lip






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