Eve V. E. Kovacs wrote:
> Hi,
> Maybe someone has some suggestions for the following problem.
> I have an SL4.4 system with 2 SATA drives configured as a RAID 1.
> As of last Friday, the system will not boot. It doesn't even get as far as
> displaying the kernel screen. I am able to boot the system from the
> rescue CD. When I do so, the disk look normal. The RAID is up and
> running and I can see the filesystems.
>
> So, I suspected that the MBR somehow got corrupted, and decided to try
> grub-install to rewrite the MBR.
>
> This didn't work...the commands I used and errors I got are listed below:
>
> grub-install hd0
> I got the error:
> /dev/md0 does not have any corresponding BIOS drive
>
> grub-install /dev/sda (note cat /proc/mdstat lists RAID partitions as
> /dev/sda1 etc)
> I got the error:
> /dev/sda does not have any corresponding BIOS drive
>
> grub-install /dev/hda
> I got the error:
> /dev/hda: Not found or not a block device
>
>
> So, how do I repair the MBR on a raided system drive? What is the
> install device that I need?
>
> Of course, this may not be the problem at all. If anyone has ideas on
> what else I should try, please let me know.
>
> Eve
Hi Eve,
Michael Mansour from this list provided this to me when I encountered
the same problem. I've also attached a note to myself about prepping
raid disks after installation. Basically, to be sure that the MBRs on
each of the raided disks are properly updated. This, of course, applies
only to a raided system with / and /boot on it.
Cheers! Ken
--His response------------------------------------------------------
If grub hangs it sometimes means that the boot manager isn't on the MBR
correctly.
What I always do in these cases is boot from rescue and run grub, then
type in:
root (hd0,0)
setup (hd0)
then boot, or just:
grub-install /dev/device
Of course all the above depends on their device name / grub numbering.
Michael.
Save the partition info
-----------------------
sfdisk -d /dev/hda > partitions.hda
sfdisk -d /dev/hdb > partitions.hdb
-d saves the partition information in a format which sfdisk can use to
restore the partitions.
Install grub on mbr's of both disks
-----------------------------------
grub> find /grub/stage1
(hd0,0)
(hd1,0)
Notation means that /boot is on hda1 and hdb1; hd(0,1) is hd(a,b) and the
second number is the partition number. 0 means 1
To install grub on the mbr of each disk
grub> device (hd0) /dev/hda
grub> root (hd0,0)
grub> setup (hd0)
Repeat for the next disk
grub> device (hd0) /dev/hdb
grub> root (hd0,0)
grub> setup (hd0)
If SCSI, then it's /dev/sda and /dev/sdb
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