Grub and old hard drives

[Karl Larsen]

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 :-(

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.

Assuming this is possible I will let the list know.

Karl

[Timothy Murphy]

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 :-(
> 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.
> Assuming this is possible I will let the list know.

I think you need to distinguish between the grub loader proper,
and the grub support files in /boot .

You can put either on either (or both) disks.
But if the loader is in the sdb/hdb MBR
you'll have to tell the BIOS to look there.
By default it will look in the sda/hda MBR.

I presently have /boot on sdb, and copies of the grub loader
on sda and sdb, in case something nasty happens to the rather old sda.

[Karl Larsen]

Timothy Murphy wrote:
> 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 :-(
> > 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.
> > Assuming this is possible I will let the list know.
>
> I think you need to distinguish between the grub loader proper,
> and the grub support files in /boot .
>
> You can put either on either (or both) disks.
> But if the loader is in the sdb/hdb MBR
> you'll have to tell the BIOS to look there.
> By default it will look in the sda/hda MBR.
>
> I presently have /boot on sdb, and copies of the grub loader
> on sda and sdb, in case something nasty happens to the rather old sda.

Well I have /boot on several partitions but the one used is on 
/dev/hdb5 now. The grub loader is on /dev/hda. I would like to put on 
/dev/hdb but it's not clear how to do that. Can you recall? Was it using 
grub-install or some other way? I will see if there is help for grub 
install.

Karl

[Mike C]

Karl Larsen <k5di <at> zianet.com> writes:
> /dev/hdb5 now. The grub loader is on /dev/hda. I would like to put on 
> /dev/hdb but it's not clear how to do that. Can you recall? Was it using 
> grub-install or some other way? I will see if there is help for grub 
> install.

You can boot a rescue disc and then use the command
grub-install /dev/hdb (or use grub-install from your running system.

See http://www.gnu.org/software/grub/manual/html_node
/Installing-GRUB-using-grub_002dinstall.html

The above url is one line!

Also man grub-install in Fedora will give help.

[Thufir]

On Fri, 29 Jun 2007 13:05:57 -0600, Karl Larsen wrote:
> 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 :-(

With Fedora 7 being a live cd, doesn't that help to make it easier?

I like your proactive attitude :)

-Thufir

[Tim]

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).