9fans archive / 2001 / 02 / 423 /    prev next

From: "Mark C. Otto" <Mark_Otto@FWS.Gov>
Subject: [9fans] MBR Problems with Install
Date: Thu, 22 Feb 2001 08:18:11 -0500

During my install of plan9 on a Micron doing a bootsetup making plan9 the active
partition, I corrupted the MBR.  The computer was backed up and I fixed the MBR
but such a basic problem was disconcerting.  Not that I want to, but I could
probably duplicate the problem if it would help.

I am trying to dual boot 29 July 2000 (Vita Nuova CD) plan9 distribution 
on a Micron with 2GB win98 and 1GB plan9 partitions.  The install went 
fine after adding a line to the VGADB.  I did bootsetup twice: once for 
a plan9 active partition and again for a boot floppy.  When I rebooted 
from the sdC0, I got the following:

MBR..I/O error
Press almost any key to reboot...

Booting from the floppy works fine.  I used disk/fdisk to make the windows
partition the active partition with the same result.  The plan9 and dos fdisks
don't find a problem with the partition tables.  The dos scandisk can check the
win98 partition.  From reading prep(8), used 

disk/mbr -m /386/mbr /dev/sdC0/data

but this did not help.  I was a little bolder because the machine was backed up.
I found in 9fans that Ture P}lsson (16 Aug 1995 13:20:54 -0400) used the dos
fdisk /mbr to restore the mbr.  This and restoring some of the files fixed the
MBR.  Was the large 2GB win98 partition too big?  I thought that problem was
fixed with this distribution.