[BlueOnyx:08488] Re: MBR lost

[Michael Stauber]

Hi Tobias,

> At the end of the now successful system start I
> saw a message like (its not the exact message, just from my memory)
> "writing sysconfig to harddisk 0"
> "writing sysconfig to harddisk 1"
> 
> what I suspect to be the output of the process that is destroying the
> boot records on my harddisks. Because I tested it with a second reboot
> and reproduced the problem: the system did not find anything on its
> disks.
> 
> Does somebody know the problem and maybe a solution?

What you saw there was probably the output of this command:

/etc/init.d/fix_grub stop

It runs as /etc/rc3.d/S80fix_grub during shutdown/reboot on a system with 
software-raid.

Typical output looks like this:

[root at delve ~]# /etc/init.d/fix_grub stop
Rebuilding grub: 
Probing devices to guess BIOS drives. This may take a long time.


    GNU GRUB  version 0.97  (640K lower / 3072K upper memory)

 [ Minimal BASH-like line editing is supported.  For the first word, TAB
   lists possible command completions.  Anywhere else TAB lists the possible
   completions of a device/filename.]
grub> root (hd0,0)
 Filesystem type is ext2fs, partition type 0xfd
grub> setup (hd0)
 Checking if "/boot/grub/stage1" exists... no
 Checking if "/grub/stage1" exists... yes
 Checking if "/grub/stage2" exists... yes
 Checking if "/grub/e2fs_stage1_5" exists... yes
 Running "embed /grub/e2fs_stage1_5 (hd0)"...  15 sectors are embedded.
succeeded
 Running "install /grub/stage1 (hd0) (hd0)1+15 p (hd0,0)/grub/stage2 
/grub/grub.conf"... succeeded
Done.
grub> root (hd1,0)
 Filesystem type is ext2fs, partition type 0xfd
grub> setup (hd1)
 Checking if "/boot/grub/stage1" exists... no
 Checking if "/grub/stage1" exists... yes
 Checking if "/grub/stage2" exists... yes
 Checking if "/grub/e2fs_stage1_5" exists... yes
 Running "embed /grub/e2fs_stage1_5 (hd1)"...  15 sectors are embedded.
succeeded
 Running "install /grub/stage1 (hd1) (hd1)1+15 p (hd1,0)/grub/stage2 
/grub/grub.conf"... succeeded
Done.
grub> quit
[root at delve ~]# 

Actually /etc/init.d/fix_grub is there to prevent the loss of the MBR. We 
never really identified what caused the sporadic loss of MBR on a software 
RAID1 system. So we eventually added this script to re-setup Grub every time 
the system reboots. I'm not particularly happy with it either, but this work 
around typically works fine.

-- 
With best regards

Michael Stauber