cannot see Windows after installing FreeBSD

Malcolm Kay malcolm.kay at
Wed Sep 29 05:50:25 PDT 2004

On Tue, 28 Sep 2004 04:48 am, Saccheen Martin wrote:
> Hi,
> Thank you for your input. As I said before, I am a
> newbie and I am just learning FreeBSD. I have no
> problem formatting the 80G and the 4.3G hard drives
> and reinstalling both WIndows XP and FreeBSD. I just
> want to make sure that I do it right the next time.
> This is really a learning process for me.
> Hence, my question is if I make the 80Gig the master
> and the 4.3G, the slave, and I install Windows XP on
> the 80G hard drive, can I install FreeBSD on the 4.3G
> hard drive and not have its boot sector overwrite the
> Windows boot files? I am asking this question because,
> even though the boot sector for FreeBSD will be on the
> slave hard drive, it still requires that its boot
> sector be on the master as well, so that I can have
> the option of booting Windows or FreeBSD on startup...

There are boot 'files' in the MBR (the first sector of 
one or more of the disk drives) and the first sector of 
each bootable slice (partition in MS terminology). The 
first of these is more or less OS independent -- in one 
way or another it passes on the boot activity to another
MBR on another disk or to a boot sector heading a slice.

Typically the boot sector at the head of the slice marked 
bootable on the first disk as seen by the BIOS is selected.
But with the standard FreeBSD MBR this selection can be 
chosen by the operator at boot time. Using the FreeBSD MBR
allows booting most OS including MS ones.

System selection in WNT (including W2K and WXP) is quite 
different. The installation uses a straight forward MBR
but replaces the boot 'file' at the head of the first
slice with bootable filesystem understood by MS with a new
one that loads the NTLDR program from that slice. The original
boot sector from the slice is copied into the file system. 
On execution NTLDR offers a menu choice selecting the newly 
installed OS (which might be on a different disk or slice) 
or the original system on that slice by executing the copy 
stowed away.

So if you make the 80G drive master and install WXP there
using the entire drive then NTLDR should install on that disk
and be safe from any installation of FreeBSD on the slave.
And this should remain OK even after installing the FreeBSD
MBR on the master drive.

If you install (or reinstall) WXP after installing FreeBSD
you may (probably will) find that the MS installation has 
overwritten your MBR on the master drive and the system 
will boot directly into WXP without offering a FreeBSD 
choice. This can be fixed by booting again from the FreeBSD 
installation CD and putting the FreeBSD MBR back.

It is also possible to use the standard MBR and make 
FreeBSD an option offered by NTLDR which is fairly straight
forward when both OS are on the master drive but gets a bit
tricky to setup when you need to switch to FreeBSD on the 
slave drive. In either case I can't recall exactly what is 
required in either case, but I've certainly successfully 
used the first in the somewhat distant past.

Hope this helps -- I'm not sure that my description is clear.

> --- Malcolm Kay <malcolm.kay at> wrote:
> > On Mon, 27 Sep 2004 07:17 am, Saccheen Martin wrote:
> > > Hi,
> > > I still cannot boot Windows so I set the BIOS to
> >
> > boot
> >
> > > from the slave hard disk that has Windows first
> >
> > and it
> >
> > > gave me the following error:
> > >
> > > NTLDR is missing
> > > press ATL-CTRL-DEL to restart
> >
> > It is my understanding that on installation windows
> > by default
> > places NTLDR is the first file system which is
> > understood by the MS software. So if the 4.3G had
> > some MS
> > file system when you installed XP on the 80G drive
> > then
> > the chances are that NTLDR was placed on the 4.3G
> > drive and
> > is now overwritten by FreeBSD.
> >
> > I would expect that a MS expert might be able to
> > replace the
> > NTLDR file and reconstruct the data file that goes
> > with it;
> > but this is outside my ken.
> >
> > Malcolm

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