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Old 06-09-2008, 08:40 PM
Bowie Bailey
 
Default Confirming grub installation

I have two drives in a software mirror. Other than setting the bios to
boot from the second drive, is there any way to confirm that grub is
installed properly on the second drive?

--
Bowie
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Old 06-10-2008, 01:03 PM
"Peter Farrell"
 
Default Confirming grub installation

When installing CentOS - sometimes the RAID-1 /boot partition, usually
/dev/md0 fails to boot.

The bug is known and exists on the bugtracker for CentOS as well as RedHat.

The fix is to re-install GRUB on on each partition of the RAID-1 array.

I think you could use the same method to answer your question.

1. boot server w/ any 'Disk-1' of an installation set
at boot prompt type 'linux rescue'
Continue boot.

2. First double check your disks with the mdadm utility
# mdadm -QD /dev/md0
Make a note of every disk (you can ignore the spare)
example: /dev/{sda1, sdb1, sdc1, sdd1, sde1}

3. drop into the GRUB prompt
# grub
grub> device (hd0) /dev/sda
grub> root (hd0,0)
grub> setup (hd0)

<repeat for each drive in the array>

grub> device (hd0) /dev/sdb
grub> root (hd0,0)
grub> setup (hd0)

Rinse - Repeat, etc.

4. exit from GRUB and reboot.


If you then want to test it, disconnect one of your drives - or just
drop into grub at boot
and tell it to boot from the partition of another drive.

-Peter




2008/6/9 Bowie Bailey <Bowie_Bailey@buc.com>:
> I have two drives in a software mirror. Other than setting the bios to
> boot from the second drive, is there any way to confirm that grub is
> installed properly on the second drive?
>
> --
> Bowie
> _______________________________________________
> CentOS mailing list
> CentOS@centos.org
> http://lists.centos.org/mailman/listinfo/centos
>
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Old 06-10-2008, 02:19 PM
Bowie Bailey
 
Default Confirming grub installation

Peter Farrell wrote:
>
> 2008/6/9 Bowie Bailey <Bowie_Bailey@buc.com>:
> > I have two drives in a software mirror. Other than setting the
> > bios to boot from the second drive, is there any way to confirm
> > that grub is installed properly on the second drive?
>
> When installing CentOS - sometimes the RAID-1 /boot partition, usually
> /dev/md0 fails to boot.
>
> The bug is known and exists on the bugtracker for CentOS as well as
> RedHat.
>
> The fix is to re-install GRUB on on each partition of the RAID-1
> array.
>
> I think you could use the same method to answer your question.

<SNIP>

> If you then want to test it, disconnect one of your drives - or just
> drop into grub at boot
> and tell it to boot from the partition of another drive.

I already know how to install grub on the second drive. The issue is
that this is a production server and I'm trying to avoid rebooting it if
possible.

I'm looking for a way to determine whether grub is installed on a drive
WITHOUT having to actually attempt to boot from it. If I redo the
installation, then I can be sure it's installed, but if it's already
there, I'd rather leave it alone. There's no point in messing with it
if it's already installed.

--
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Old 06-10-2008, 02:33 PM
Kai Schaetzl
 
Default Confirming grub installation

Bowie Bailey wrote on Tue, 10 Jun 2008 10:19:34 -0400:

> I'm looking for a way to determine whether grub is installed on a drive
> WITHOUT having to actually attempt to boot from it. If I redo the
> installation, then I can be sure it's installed, but if it's already
> there, I'd rather leave it alone. There's no point in messing with it
> if it's already installed.

You could dd the MBR to a file and then examine both. You could diff them,
I think they should be identical, should they?

Kai

--
Kai Schätzl, Berlin, Germany
Get your web at Conactive Internet Services: http://www.conactive.com



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