From owner-freebsd-hackers@FreeBSD.ORG  Fri Mar  6 15:26:00 2009
Return-Path: <owner-freebsd-hackers@FreeBSD.ORG>
Delivered-To: freebsd-hackers@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34])
	by hub.freebsd.org (Postfix) with ESMTP id 577F01065674
	for <freebsd-hackers@freebsd.org>; Fri,  6 Mar 2009 15:26:00 +0000 (UTC)
	(envelope-from psteele@maxiscale.com)
Received: from exprod7og101.obsmtp.com (exprod7og101.obsmtp.com [64.18.2.155])
	by mx1.freebsd.org (Postfix) with SMTP id 123E48FC08
	for <freebsd-hackers@freebsd.org>; Fri,  6 Mar 2009 15:26:00 +0000 (UTC)
	(envelope-from psteele@maxiscale.com)
Received: from source ([209.85.198.242]) by exprod7ob101.postini.com
	([64.18.6.12]) with SMTP
	ID DSNKSbFAh7OqOqFmROChpPnuRyIpp+HsDh5M@postini.com;
	Fri, 06 Mar 2009 07:26:00 PST
Received: by rv-out-0708.google.com with SMTP id l33so489177rvb.0
	for <freebsd-hackers@freebsd.org>; Fri, 06 Mar 2009 07:25:57 -0800 (PST)
Received: by 10.140.142.15 with SMTP id p15mr1330648rvd.177.1236353157618;
	Fri, 06 Mar 2009 07:25:57 -0800 (PST)
Received: from localhost ([76.231.178.131])
	by mx.google.com with ESMTPS id b39sm2011609rvf.9.2009.03.06.07.25.56
	(version=SSLv3 cipher=RC4-MD5); Fri, 06 Mar 2009 07:25:57 -0800 (PST)
Date: Fri, 6 Mar 2009 07:25:38 -0800 (PST)
From: Peter Steele <psteele@maxiscale.com>
To: freebsd-hackers@freebsd.org
Message-ID: <27198392.361236353137467.JavaMail.HALO$@halo>
In-Reply-To: <gordnd$ie4$1@ger.gmane.org>
MIME-Version: 1.0
Content-Type: text/plain; charset=utf-8
Content-Transfer-Encoding: 7bit
X-Content-Filtered-By: Mailman/MimeDel 2.1.5
Subject: Re: How to tear down a geom mirror?
X-BeenThere: freebsd-hackers@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: Technical Discussions relating to FreeBSD
	<freebsd-hackers.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-hackers>, 
	<mailto:freebsd-hackers-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-hackers>
List-Post: <mailto:freebsd-hackers@freebsd.org>
List-Help: <mailto:freebsd-hackers-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-hackers>,
	<mailto:freebsd-hackers-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Fri, 06 Mar 2009 15:26:01 -0000

>Yes. The "clear" commands usually just zero-out the last sector of the 
>underlying provider (doesn't matter if it's a drive, slice or something 
>altogether different) so you don't have to do it manually. 

So, as a generic solution then I could just iterate through all slices of all drives and run "gmirror clear" on each, and run dd to clear the first sectors. What btw is in these first sectors? I use this command because I saw it being done in one of the gmirror tutorials. I understand what the gmirror clear command does, but what is the dd command clearing?