MBR repair

K05T9 · 05-05-2007, 11:39 AM

yes, i had 3 partitions and cfdisk shows them correctly(the size is the same). Only fdisk shows this extended partition.

allend · 05-05-2007, 11:48 AM

I think you have created an erroneous W95 extended partition.
Try using cfdisk to delete the hdc2 partition.

K05T9 · 05-05-2007, 12:02 PM

are u sure it would not delete cylinders from 877 to 4870?

allend · 05-05-2007, 12:06 PM

It will not delete any of your data from the disk. It will only change the contents of the MBR. You can always change it back if it does not work.

K05T9 · 05-05-2007, 12:15 PM

could u tell me how to backup mbr in slackware?
Or i should just copy the partition table file somewhere?

allend · 05-05-2007, 12:20 PM

From http://www.linuxquestions.org/questi...06#post1848006

Quote:

In this example, sda is the source. Sdb is the target. Do not reverse the intended source and target. Surprisingly many people do. Notrunc means 'do not truncate the output file'. Noerror means to keep going if there is an error. Normally dd stops at any error.
Copy MBR only of a hard drive: [/color]
Code:

dd if=/dev/sda of=/home/sam/MBR.image bs=446 count=1

This will copy the first 446 bytes of the hard drive to a file. If you haven't already guessed, reversing the objects of if and of, in the dd command line reverses the direction of the write.

K05T9 · 05-05-2007, 12:36 PM

if i delete extended partition, it deletes all partitions except first one.

K05T9 · 05-05-2007, 12:44 PM

i guess the boot sector of primary windows partition is broken, and i need to repair it somehow.

syg00 · 05-05-2007, 05:52 PM

First, do *not* go deleting any partitions. That partition layout is fine.

Quote:

When i load windows, it just does not find the partition and asks to reboot.

What does this mean ???.
Explain fully - are these messages from Windows or grub ???. That is, is Windoze booting successfully (from grub) but then dying ???.

K05T9 · 05-05-2007, 05:59 PM

i see boot screen. choose windows. and error message shows up, don't remember exactly, but it's mbr error.
I can go for restart if it is so important, but, believe me, it's not windows error.

syg00 · 05-05-2007, 06:39 PM

Forget I mentioned grub

Have you tried running a lilo command to make sure that is o.k. ???.

K05T9 · 05-05-2007, 06:43 PM

i tried lilo.
Oh, there's an error message: a disk read error occured

K05T9 · 05-05-2007, 07:10 PM

there is a quite big post about this problem

http://www.hardwareanalysis.com/cont...c/19004/?o=280

ludist · 05-06-2007, 04:26 AM

Quote:

Originally Posted by allend

Yes, there is a problem.
hdc1 starts at 1 and ends at 876.
hdc2 starts at 877 and ends at 4870. - This end point is wrong.
hdc5 starts at 877 and ends at 4159. - This start point is wrong.
hdc6 starts at 4160 and ends at 4870.

NO! It's RIGHT!

hdc2 is extended partition and "embraces" hdc5 and hdc6!

to fix:
from Slackware. Check if a mbr backup exists in /boot in file like boot.xxxx
from Windows. Put your cd, boot in recovery console. fixmbr and fixboot (I don't remember the exact commands) fixmbr /? to learn. With fixmbr from Windows (probably with Slackware too) you gone LOOSE access to slackware. So, you are gonna need to boot with slack cd 1. I chroot to my root partition and ran lilo again.

mkdir /mnt/myslack
mount /dev/hdc6 /mnt/myslack
chroot /mnt/myslack
vi /etc/lilo.conf (if needed)
lilo

probably you are ok now..

Make a backup of your MBR because it's annoying to do all this stuff.

onebuck · 05-06-2007, 09:40 AM

Quote:

Originally Posted by ludist

NO! It's RIGHT!

hdc2 is extended partition and "embraces" hdc5 and hdc6!

to fix:
from Slackware. Check if a mbr backup exists in /boot in file like boot.xxxx
from Windows. Put your cd, boot in recovery console. fixmbr and fixboot (I don't remember the exact commands) fixmbr /? to learn. With fixmbr from Windows (probably with Slackware too) you gone LOOSE access to slackware. So, you are gonna need to boot with slack cd 1. I chroot to my root partition and ran lilo again.

mkdir /mnt/myslack
mount /dev/hdc6 /mnt/myslack
chroot /mnt/myslack
vi /etc/lilo.conf (if needed)
lilo

probably you are ok now..

Make a backup of your MBR because it's annoying to do all this stuff.

Hi,

I agree with your solution in part. I would add for the 'lilo';

Code:

#lilo -v -t -b /dev/hda     #change to the user /dev/hd
                            #-t will test lilo 'do man lilo'
#lilo -v -b /dev/hda        #write lilo to MBR /dev/hda

The OP should 'man lilo' and 'man lilo.conf' for more information.
As for the fixmbr
command Microsoft shows the format. For the fixboot
command example.

If the OP uses the Microsoft commands then these will restore the windows. Then the OP will need to use the chroot series for the Slackware that 'ludist' suggests to get the bootloader working again.

Note: A lot of newbies confuse the use of the extended partitions. If you create a extended partition on /dev/hda as /dev/hda3 the first partition within the extended /dev/hda3 will be /hda5. This would be so in any of the partitions that you would create as extended, be it /hda1, /hda2, /hda3 or /hda4. The first partition within the extended will be /hda5 on the defined extended device.

You could reference the partition section of the 'The Linux System Administrator's Guide: Version 0.7'.