[CentOS] Confirming grub installation

Peter Farrell peter.d.farrell at gmail.com
Tue Jun 10 13:03:58 UTC 2008

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.


2008/6/9 Bowie Bailey <Bowie_Bailey at 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
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