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Date:      Tue, 28 Oct 2008 05:22:31 -0700
From:      Jeremy Chadwick <koitsu@FreeBSD.org>
To:        Bullet 446 <bullet446@googlemail.com>
Cc:        freebsd-questions@freebsd.org
Subject:   Re: Zero-Fill format before installation
Message-ID:  <20081028122231.GB49298@icarus.home.lan>
In-Reply-To: <786a1e4f0810280321w7aa8894fnb736fa4c83d3ef5e@mail.gmail.com>
References:  <786a1e4f0810280321w7aa8894fnb736fa4c83d3ef5e@mail.gmail.com>

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On Tue, Oct 28, 2008 at 10:21:00AM +0000, Bullet 446 wrote:
> I have a remote machine with KVM access that I'd like to format and
> reinstall FreeBSD 7.0. I've succeded in formatting /dev/ad6 but not the main
> drive, /dev/ad4.
> Is it possbile to zero-fill format during the installation instead of simply
> deleting and recreating partitions?
> 
> I've tried booting into single user mode without any success:
> # umount -a
> umount: /cdrom: not a file system root directory
> umount: /var: not a file system root directory
> umount: /usr: not a file system root directory
> umount: /tmp: not a file system root directory
> # dd if=/dev/zero of=/dev/ad4
> dd: /dev/ad4: Operation not permitted

You need to tell GEOM to allow you to overwrite the MBR at the start
of the disk.

sysctl kern.geom.debugflags=16 then do the dd again.

I STRONGLY recommend you add "bs=64k" to that dd statement, or else it's
going to take a million years.  :-)

-- 
| Jeremy Chadwick                                jdc at parodius.com |
| Parodius Networking                       http://www.parodius.com/ |
| UNIX Systems Administrator                  Mountain View, CA, USA |
| Making life hard for others since 1977.              PGP: 4BD6C0CB |




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