Running "grub-install /dev/sda" in a live environment
"fixes" the
machine so it will boot.
Unless there's a good reason not to though, I'd like to know why the
current method doesn't work, and find a general solution that will
work for any setup. See my last email.
And also, I can't seem to find "grubby". It's not included on the
fedora rescue cd or ubuntu live cd, and the fedora live cd keeps
giving me a kernel panic when I try to boot it. But that's a separate
issue for now.
-Andrew
grub-install is also fine. Grubby is what you use to manipulate
grub.conf once installed. Apologies for the confusion there.
--Michael
On Wed, Aug 20, 2008 at 2:25 PM, Andrew Brown <ambrown4(a)ncsu.edu
<mailto:ambrown4@ncsu.edu>> wrote:
On Wed, Aug 20, 2008 at 7:44 AM, Michael DeHaan
<mdehaan(a)redhat.com <mailto:mdehaan@redhat.com>> wrote:
Andrew Brown wrote:
> On Tue, Aug 19, 2008 at 6:16 PM, Michael DeHaan
<mdehaan(a)redhat.com <mailto:mdehaan@redhat.com>
> <mailto:mdehaan@redhat.com <mailto:mdehaan@redhat.com>>>
wrote:
>
> Andrew Brown wrote:
> > Okay, a few things since yesterday:
> > I'm not worrying about the hard drive device issue for the
> moment, it
> > seems to be related to whether the bladecenter media
tray is
> assigned
> > to that blade or not.
> >
> > I've also edited the code to ignore listed partitions
of type
> "Empty"
> > or "Extended"
>
> Is there a new attachment we can look at for this?
>
>
> I've attached the most recent base.cfg which contains the
code. Keep
> in mind that today I did things manually though, not using
the script.
>
>
>
> >
> > But somehow the process isn't working. I followed the
process very
> > closely of xcat, a similar provisioning engine. After
taking and
> > restoring an image, it doesn't boot.
> >
> >
> > I tried the process manually today. That is, I booted
with a
> live cd
> > and ran each command myself. Saved the mbr, saved the
partition
> table
> > with sfdisk, and saved the contents of each partition
of a freshly
> > installed linux installation.
> >
> > Then I went to the next blade, identical hardware and
setup, and
> > booted the live cd up.
> > -Restored partition entries with sfdisk
> > -Restored mbr with dd
> > -Restored partitions again with sfdisk. I don't fully
> understand why
> > it's done again, this was just following the xcat
process (for
> which
> > I can post the exact code if anyone's curious).
> > -And of course restore all partitions one at a time
> >
> > When I tried to boot it back up, it got as far as printing
> "GRUB" and
> > hung there. I need some help here, I'm not sure
what's going on.
>
> One thing to check is to stop before rebooting and see
if grub is
> installed correctly, or if any errors happen during
grub-install.
> For
> that, it may be worth running through the script line by
line or at
> least logging the output of each step w/ debug output
printed before
> each command as needed.
>
>
> Like I said, I did the entire procedure manually... entered each
> command myself so I knew exactly what was running. Once I
get it
> working manually, I can easily find out if my script is
doing things
> any differently.
>
> How do I tell if grub is installed correctly?
"grubby" has some probe options that should do this. See
"man grubby"?
>
>
>
>
> >
> > I tried a different order to restoring partition/mbr
info: Restore
> > partition stuff with sfdisk, and then the mbr with dd.
I was
> thinking
> > sfdisk may have overwritten the mbr or something, but
I got the same
> > results.
>
> Grub lives in the MBR, though are you calling
grub-install after
> all of
> that?
>
>
> Right. I'm not calling grub-install. I didn't think it was
> necessary. Grub lives in the mbr, which is the first 512
bytes of the
> drive. I'm saving the mbr to a file and restoring it back.
Shouldn't
> that be sufficient?
In theory, assuming it's not a GPT partition /and/ grub lives
in the MBR
(both of which can't really be assumed), yes.
It's best to use grubby, the command line tool, for manipulating
grub. As a bonus it also knows how to manipulate lilo and
elilo.
There is some code in koan that references a few common grubby
commands,
though you'll probably want to change this around.
--bad-image-ok does not work, but otherwise what you see koan
using for
the live CD is close.
Also there are some bits of the live config script that are using
grub-install.
So I suppose I'm wrong in assuming that saving the mbr+partition
layout and each partitions' contents, and then restoring each
component is not sufficient for perfectly duplicating a hard
drive. Where else could data lie?
I'll look into using grubby to make sure grub is installed, but I
still don't know why this doesn't work as is, things should be
restored exactly as they were, right?
And further, what about systems that don't use grub, such as
windows? How are we going to do this so that it's still cross
platform?
-Andrew
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