update-grub help

[Goh Lip]

On 05/27/2010 11:03 AM, Tom H wrote:
> On Wed, May 26, 2010 at 10:48 PM, Goh Lip<g.lip at gmx.com>  wrote:
>> On 05/27/2010 03:23 AM, Goh Lip wrote:
>>
>>> Re; use of "search xxxxx --set xxx " instead of "set root=(hdx,y)
>>> and /dev/sdxy" : trying to get you some definitive  information on this,
>>> but so far, most of this is "inferred"  through the grub developers
>>> mailing list and of course my own experience in failure to boot due to
>>> 'movement' in hdx,y and /dev/sdc or /dev/sdd, particularly in grub
>>> legacy. Will post to you if I get more information. But I am reluctant
>>> to send info that is not indisputatble.
>>
>> Tom, refer https://help.ubuntu.com/community/UsingUUID
>>/
>> First line writes:
>>
>> Linux now prefers to use UUID (Universally Unique Identifier), LABEL, or
>> symlinks to identify media storage devices on a system. Directly using
>> /dev/hd*# or /dev/sd*# is no longer preferred since these device
>> assignments can change between system boots:
>
> I am not advocating the use of /dev/sdXY, far from it.
>
> The files in /dev/disk/by-id and /dev/disk/by-uuid are unique symlinks
> to /dev/sdXY and are created by udev.
>
> Instead of using "root=UUID=<uuid>", you can use
> "root=/dev/disk/by-uuid/<uuid>" to refer in as uniquely a way to the
> same partition.
>
> It looks like OpenSuse uses "root=/dev/disk/by-id/<id>" (maybe there
> isn't a "root=ID=<id>" option) and it is just as valid and unique a
> way as a uuid.
>

Yes, understood. Got it. But when Dave deletes the "search xxxxxx set 
xxx", this means using the set root=(hdx,y) which is unreliable and will 
set that as the root. Even if he specify kernel correctly,as in "linux 
/boot/vmlinuz-xxx xxxxx root=/dev/disk/by-id/xxxxxx", his "root 
partition" may be wrong and will not boot.

Regards - Goh Lip

--