Problematic dual boot

Gene Heskett gene.heskett at
Wed Mar 18 14:00:00 UTC 2009

On Wednesday 18 March 2009, Eberhard Roloff wrote:
>Eberhard Roloff wrote:
>> No need to reinstall Kubuntu. Just save your mbr BEFORE you reinstall
>> windows. You can do it like this:
>> if=/dev/sda1 of=sda1_bootsector bs=512 count=1
>> Then reinstall Windows which will recklessly overwrite the MBR.
>> Finally save the then existing Windows-MBR (just to be safe) and play
>> back the original MBR, that you saved before installing Windows.
>sorry I forgot:
>For restoring your mbr, reverse the save procedure, like this:
And in both cases you have the potential to be wrong.  You are selecting the 
first sector of the partition, not the first sector of the device, thereby 
missing LSN0, the mbr the bios will check on that drive first.

>dd if=sda1_bootsector of=/dev/sda1 bs=512 count=1

sudo dd if=/dev/sda of=/sda_bootsector bs=512 count=1
sudo dd if=/sda_bootsector of=/dev/sda bs=512 count=1

Remove the sudo if already root, not advisable for *ubuntu's.

This is the true location of the mbr.
>Actually afaik, bs and count parameters are not really needed for
>restore since the saved mbr will not be larger than you specified at
>save time. I just routinely add those parameters to better memorize,
>what to do.
>> For the last two steps you will most probably a Boot CDRom.
>> Have some fun
>> Eberhard

Cheers, Gene
"There are four boxes to be used in defense of liberty:
 soap, ballot, jury, and ammo. Please use in that order."
-Ed Howdershelt (Author)
Well, O.K.  I'll compromise with my principles because of EXISTENTIAL DESPAIR!

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