[nflug] Disk Image/Restore

[Jonathan Skulski]

On 7/25/06, Cyber Source <peter at thecybersource.com> wrote:
> >> If we say, put xp on a
> >> drive that previously had grub on the mbr, we could ghost, dd, tar
> >> the xp copy onto the drive and then it would fail to boot UNTIL we
> >> blank the mbr.
> >
> > Huh. I know win* does _something_ to my MBR. Because anytime I've
> > reinstalled any windows it overwrites it and I have to re-run grub
> > if I want to get to Linux. But I didn't think that the bios
> > was smart enough to look beyond the first HD sector for boot
> > information. So if I did a "dd if=/dev/zero of=/dev/hda bs=512
> > count=1" to get rid of my MBR and my windows partition is set to
> > bootable (and its the first partition) I could still boot windows?
> >
> > -Josh
>
> yes, that command is just blanking the mbr just like fixmbr (xp) and
> fdisk /mbr (dos/98)

Well Josh's question was whether or not blanking the mbr would allow
win98/xp to boot. Which it does not. I just did a

$ dd if=/dev/sda of=mbr.txt count=1 bs=512

and it was definately was not all zeros (hexdump)
then i tried a

$ dd if=/dev/zero of=/dev/sda count=1 bs=512

and it didn't boot.

Conclusive proof that:
-  Windows XP definately needs some sort of instruction in the mbr
-  fdisk /mbr != dev if=/dev/zero of=/dev/sda count=1 bs=512


jsk
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