[ILUG] System boots with disks in random order...

[Michael Watterson]

Rory Byrne wrote:
> On Mon, Dec 24, 2007 at 11:49:53AM +0100, Rory Byrne wrote:
>   
>> On Sun, Dec 23, 2007 at 09:09:35PM +0000, Kevin Lyda wrote:
>>     
>>> I have a linutop box that works very well - until I plug in a second
>>> disk. Then it doesn't tend to boot because the disks come up in a
>>> different order.
>>>
>>>       
>> Hi Kevin,
>>
>> how about adding a fallback entry, so if it fails to boot from 
>> (hd0) it just tries (hd1). 
>>
>>     default 0
>>     fallback 1
>>     
>>     title       Debian GNU/Linux, kernel 2.6.18-3-amd64
>>     root        (hd0,1)
>>     kernel      /boot/vmlinuz-2.6.18-3-amd64 root=/dev/sda2 ro
>>     initrd      /boot/initrd.img-2.6.18-3-amd64
>>     
>>     title       Debian GNU/Linux, kernel 2.6.18-3-amd64
>>     root        (hd1,1)
>>     kernel      /boot/vmlinuz-2.6.18-3-amd64 root=/dev/sda2 ro
>>     initrd      /boot/initrd.img-2.6.18-3-amd64
>>
>>     
>
> Actually, that should have read:
>
>     default saved
>     fallback 1
>
>     title         Debian GNU/Linux, kernel 2.6.18-3-amd64
>     root          (hd0,1)
>     kernel        /boot/vmlinuz-2.6.18-3-amd64 root=/dev/sda2 ro
>     initrd        /boot/initrd.img-2.6.18-3-amd64
>     savedefault   fallback
>
>     title         Debian GNU/Linux, kernel 2.6.18-3-amd64
>     root          (hd1,1)
>     kernel        /boot/vmlinuz-2.6.18-3-amd64 root=/dev/sda2 ro
>     initrd        /boot/initrd.img-2.6.18-3-amd64
>     savedefault
>
> You'd also want to do the following once to make sure the default is 
> set up correctly:
>
>     grub-set-default 0
>
> And you'd need to put an entry in your rc.local file (eg /etc/rc.local) 
> that resets the default back to 0 on a successful boot:
>
>    # /etc/rc.local
>    /usr/sbin/grub-set-default 0
>
> However, I just bothered to read Michael Watterson's post, and it 
> eclipses this one. If you're not already seeing a grub menu when you 
> boot, or being dropped to a grub shell, then nothing I've mentioned here 
> will work. 
>
> Cheers,
>
> Rory
>   
Since both devices are USB, then  both need to be bootable, and the 
different scripts on each mount everything the same way, no matter which 
device was booted from.
Since the kernel does not need to be on the bootable partition, AFAIK  
you  only  need  the Kernel on  one  disk as  long  as  both  disks are 
visible to grub on either disk.

-- 
Mike