[PLUG] grub. backups and UUIDS

Word Wizard Word.Wizard at comcast.net
Thu Apr 16 20:40:28 UTC 2009


I noticed that for some reason grub uses UUIDs to determine the location
of the kernel in the menu.lst. For some reason unknown to me, somebody
decided UUIds are preferable to the (hd0) notation I've come  know in
Windows boot.ini or the /dev/hda notation of lilo. It appears to me that
UUIds are not fixed attributes (e.g., like a serial number) of a given
piece of hardware or a reliable partition designation but change with
each installation. 

So if I install a new copy of Ubuntu Intrepid then try to put into place
the old / file system I previously tar-ed, there is a mismatch of UUIDs.
This may in fact be part of my difficulties in Intrepid restoring that
originated this thread. I think I may have installed a fresh copy of
Intrepid then tried to restore the previous / system,

Why did they migrate to UUIDs in grub?  What is the advantage? Can you
employ the other device notations in grub? Can lilo be used in Intrepid
instead? Or another boot loader?  

Thanks,  

Word Wizard 


On Wed, 2009-04-15 at 19:59 -0700, Dwight Hubbard wrote:

> Grub stores the actual physical locations of the datablocks of it's
> stage 1.5 or stage 2 files in the bootblock.  If you restore from a
> tar archive the location of the blocks for the grub stage files will
> almost certainly be different and as a result grub will generate an
> error 15 because it can't find them.  
> 
> After restoring from a tar archive you need to chroot into the newly
> restored filesystem and run a grub-install to cause the restored
> system to write the grub stage file locations to the boot block.
> 
> Or you can restore grub from the grub command.  If my memory serves
> the commands would look something like this (assuming your /boot
> filesystem (hd0,1) and you want the boot block on the first hard disk:
> root (hd0,1)
> setup (hd0)





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