From owner-freebsd-doc@FreeBSD.ORG  Fri Mar 30 03:23:15 2012
Return-Path: <owner-freebsd-doc@FreeBSD.ORG>
Delivered-To: freebsd-doc@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52])
	by hub.freebsd.org (Postfix) with ESMTP id B2A04106566B;
	Fri, 30 Mar 2012 03:23:15 +0000 (UTC)
	(envelope-from wblock@wonkity.com)
Received: from wonkity.com (wonkity.com [67.158.26.137])
	by mx1.freebsd.org (Postfix) with ESMTP id 6BE768FC14;
	Fri, 30 Mar 2012 03:23:15 +0000 (UTC)
Received: from wonkity.com (localhost [127.0.0.1])
	by wonkity.com (8.14.5/8.14.5) with ESMTP id q2U3NEDW054487;
	Thu, 29 Mar 2012 21:23:14 -0600 (MDT)
	(envelope-from wblock@wonkity.com)
Received: from localhost (wblock@localhost)
	by wonkity.com (8.14.5/8.14.5/Submit) with ESMTP id q2U3NEIv054484;
	Thu, 29 Mar 2012 21:23:14 -0600 (MDT)
	(envelope-from wblock@wonkity.com)
Date: Thu, 29 Mar 2012 21:23:14 -0600 (MDT)
From: Warren Block <wblock@wonkity.com>
To: Daniel Gerzo <danger@freebsd.org>
In-Reply-To: <alpine.BSF.2.00.1203272317290.41849@wonkity.com>
Message-ID: <alpine.BSF.2.00.1203290955380.51317@wonkity.com>
References: <alpine.BSF.2.00.1201231536490.92721@wonkity.com>
	<20120125.111625.2289296443525755896.hrs@allbsd.org>
	<7e043215e6cd0f2da324d6599c921fec@rulez.sk>
	<alpine.BSF.2.00.1203272317290.41849@wonkity.com>
User-Agent: Alpine 2.00 (BSF 1167 2008-08-23)
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; format=flowed; charset=US-ASCII
X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.2.7
	(wonkity.com [127.0.0.1]); Thu, 29 Mar 2012 21:23:14 -0600 (MDT)
Cc: freebsd-doc@freebsd.org, pjd@freebsd.org
Subject: Re: Handbook RAID1 example
X-BeenThere: freebsd-doc@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: Documentation project <freebsd-doc.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-doc>,
	<mailto:freebsd-doc-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-doc>
List-Post: <mailto:freebsd-doc@freebsd.org>
List-Help: <mailto:freebsd-doc-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-doc>,
	<mailto:freebsd-doc-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Fri, 30 Mar 2012 03:23:15 -0000

On Tue, 27 Mar 2012, Warren Block wrote:

> Procedure tested on both 9.0-RELEASE and 8.2-RELEASE.  It could stand more 
> testing.

HTML: http://www.wonkity.com/~wblock/gmirror/geom-mirror.html

And more testing does show a problem.

My tests were all using the smaller drive as the new drive (20G). 
Create a mirror using that whole drive, copy the data from the 20G 
allocated space on the original 200G drive.

But it doesn't work the other way around.  Create a mirror of the full 
larger drive, and the smaller drive cannot be inserted into it; it can't 
mirror a 200G drive.

The procedure really ought to work with different-sized drives, because 
that situation is expectable.

Telling the users that the disks must be identical is weak.  It may 
still fail because of the presence or absence of a label or other 
metadata eating one or more sectors even if the drives are identical.

Now I'm considering labeling each disk, then using gnop(8) to create a 
matching-sized device on each.  This adds more complexity, and maybe the 
thing to do is put the whole thing into a shell script.

Suggestions welcome.