[plug] grub2 and the mystery of the moving hard drives

[wolfbite]

HATE UUID (but can understand why for big servers and corporations

small servers & users, use LABELS sooooo much easier and dont have to 
worry about order.

quick google
http://www.linuxquestions.org/questions/linux-software-2/using-labels-in-grub2-how-819474/



On 16/03/12 19:15, Brad Campbell wrote:
> G'day all,
>
> I'm in the process of building a new server. It has 24 drive bays and 
> a peculiarity of the system firmware appears to be when I add or 
> remove drives, the boot drive moves around in the BIOS order. This 
> means that grub2 can rarely (if ever) find the drive its modules are 
> stored on as its root directory is hardcoded at install time. Why it 
> can't find it is a mystery to me given its stage 1 just loaded stage 
> 1.5 from the boot track, but never mind.
>
> After spending days fighting with this rotten thing booting of USB 
> rescue disks to re-install grub, I stumbled across this little trick.
>
> grub2 can have a config file embedded in its core image. Now, as is 
> typical, how you get it in there is not particularly obvious.
>
> Frustratingly grub-install has no way of letting you pass a config 
> file to embed, however grub-mkimage does. grub-install has a way of 
> letting you override which grub-mkimage it uses.
>
> I created 2 files.
>
> root at test:/root/grub2# cat grub.core.config
> search.fs_uuid root 29f53f33-f452-4382-b598-ee307a65f360
> set prefix=($root)/grub
>
> root at test:/root/grub2# cat test
> #!/bin/sh
>
> grub-mkimage -c grub.core.config $@
>
> Then installed with
> grub-install --grub-mkimage=./test /dev/sde
>
> Bingo. Grub now has its uuid search algorithm embedded along with the 
> config file and the first thing it does is search all accessible 
> partitions for the uuid and uses that to access its files. I can 
> happily rearrange disks with gay abandon and the system boots every time.
>
> Note I'm using a separate /boot partition that is plain ext2 and 
> therefore the grub files are at /grub rather than /boot/grub.
>
> I wish this was documented somewhere obvious.
>
> Regards,
> Brad
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