disklabel: Invalid signature in mbr record 0

Hello

I got this strange response when I disklabel my second hard
disk:
disklabel: Invalid signature in mbr record 0
I dont know if I am doing some in an erroneous way.

The situation is the following:
* Using NetBSD-3.1 (complete disk for NetBSD)
* Both disks are identical... brand ans model
* It occurs when second disk is new and clean. If second
disk have
   a previous NetBSD installed, the message dont occurs.
* My tests are with amd64 and i386 only. Both give the
message.
* I tested scsi and ide disks. Both give the message.

I am using the second example of manual (man disklabel(8))
(using -w and -r flags)
and I dont remenber such message in netbsd2 or older.

This is my procedure:
1) Install NetBSD from cdrom in sd0 and reboot
2) disklabel -t sd0 >> /etc/disktab
3) disklabel -w -r sd1 mydisk
and the message occurs

If I repeat the disklabel command, the message occurs again.
Am I doing something wrong?

Thanks in advance

Heron Gallegos
Saltillo Coahuila Mexico

On Sun, Dec 17, 2006 at 08:27:32PM -0600, Heron Gallegos
wrote:
> Hello
> 
> I got this strange response when I disklabel my second
hard disk:
> disklabel: Invalid signature in mbr record 0
> I dont know if I am doing some in an erroneous way.
[..]

> This is my procedure:
> 1) Install NetBSD from cdrom in sd0 and reboot
> 2) disklabel -t sd0 >> /etc/disktab
> 3) disklabel -w -r sd1 mydisk
> and the message occurs

You missed the fdisk part.

disklabel needs a MBR on that disk.
Make sure that you reserve some space at the begining of the
disk
(63 sectors) when you create the mbr label for NetBSD (type
169).
You could get into trouble if you do not reserve this space,
like
windows overwritting these sectors.

Bernd

On Mon, 18 Dec 2006, Bernd Ernesti wrote:
> You missed the fdisk part.
>
> disklabel needs a MBR on that disk.
> Make sure that you reserve some space at the begining
of the disk
> (63 sectors) when you create the mbr label for NetBSD
(type 169).
> You could get into trouble if you do not reserve this
space, like
> windows overwritting these sectors.

Thanks, Bernd.

I ran "fdisk -u sd1" using the default (suggested)
values. Now
the output of "fdisk sd0" and "fdisk
sd1" shows both disks are
exactly the same values. Thanks again, Bernd.

At this point, (my curiosity and previous to disklabel), I
ran the
commands "disklabel sd0" and "disklabel
sd1" to see how is my
second disk now and how it should be. I found some
interesting
differences: (sd0 was fdisked and disklabeled by sysinst and
sd1
by me)

disk    sd0     sd1
type:   unknown SCSI
disk:   mydisk  mydisk
label: <empty>  fictitious
rpm:    3600    10025

My fdisk detects correct values for type and rpm in sd1.
This last comment was just for curiosity.

Thanks

Heron Gallegos
Saltillo Coahuila Mexico