Grub and old hard drives

Tim ignored_mailbox at
Sat Jun 30 08:50:05 UTC 2007

On Fri, 2007-06-29 at 13:05 -0600, Karl Larsen wrote:
> For several years I have let the anaconda loader put the grub boot 
> message in the spot for such things on /dev/hda/. Fine, a couple of 
> years later I bought a much bigger hard drive and this Linux is on that. 
> But Grub is still using /dev/hda/.
>     These are both Western Digital hard drives and I have had good luck 
> with them. But the first to fail will be the oldest I expect. When that 
> happens Grub will fail. This is a real hard thing to fix :-(

No, not really.  It's quite easy.

>     So I have a plan. First read "Info Grub" and see how to put a Grub 
> boot in the boot section of /dev/hdb/. This I think is pretty simple. I 
> can do this today. But how to cause the file /boot/grub/grub.conf to use 
> this new boot point may be difficult. 

One simple approach is like the following example, it's not an exact
recipe, but a vague explanation of the process.

     1. Become root.
     2. Get into the grub shell by typing into the command line:  grub
     3. Type the "root" command followed by the drive where your /boot
        partition is to be, and by inference the grub/ sub-directory.
        You might do it like: root(hd0,0)
     4. Type the "setup" command followed by the drive you want GRUB to
        be set up into its MBR.  e.g. root(hd0)
     5. Type into the grub shell:  quit
     6. Make sure that you have the right grub.conf file in
        that /boot/grub/, and the root= kernel parameter points to the
        right partition (this is yet another case where partition labels
        really help).

That's about all there is to it.  Just a few steps.  There's any number
of examples on the web that outline exactly how to do it.  But
understanding the methodology ought to make it easier to follow the
manual or any other recipes.  Remember that GRUB uses the (hd0) and
(hd0,0) scheme of referring to drives and partitions, different from the
usual Linux methodology (/dev/sda).

[tim at bigblack ~]$ rm -rfd /*^H^H^H^H^H^H^H^H^H^Huname -ipr
2.6.21-1.3228.fc7 i686 i386

Using FC 4, 5, 6 & 7, plus CentOS 5.  Today, it's FC7.

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