From owner-freebsd-geom@FreeBSD.ORG  Thu Jul  9 11:53:09 2009
Return-Path: <owner-freebsd-geom@FreeBSD.ORG>
Delivered-To: freebsd-geom@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34])
	by hub.freebsd.org (Postfix) with ESMTP id 187281065676
	for <freebsd-geom@freebsd.org>; Thu,  9 Jul 2009 11:53:09 +0000 (UTC)
	(envelope-from gcubfg-freebsd-geom@m.gmane.org)
Received: from ciao.gmane.org (main.gmane.org [80.91.229.2])
	by mx1.freebsd.org (Postfix) with ESMTP id CB0DE8FC23
	for <freebsd-geom@freebsd.org>; Thu,  9 Jul 2009 11:53:08 +0000 (UTC)
	(envelope-from gcubfg-freebsd-geom@m.gmane.org)
Received: from list by ciao.gmane.org with local (Exim 4.43)
	id 1MOsBV-000374-1e
	for freebsd-geom@freebsd.org; Thu, 09 Jul 2009 11:53:05 +0000
Received: from lara.cc.fer.hr ([161.53.72.113])
	by main.gmane.org with esmtp (Gmexim 0.1 (Debian))
	id 1AlnuQ-0007hv-00
	for <freebsd-geom@freebsd.org>; Thu, 09 Jul 2009 11:53:05 +0000
Received: from ivoras by lara.cc.fer.hr with local (Gmexim 0.1 (Debian))
	id 1AlnuQ-0007hv-00
	for <freebsd-geom@freebsd.org>; Thu, 09 Jul 2009 11:53:05 +0000
X-Injected-Via-Gmane: http://gmane.org/
To: freebsd-geom@freebsd.org
From: Ivan Voras <ivoras@freebsd.org>
Date: Thu, 09 Jul 2009 13:52:53 +0200
Lines: 42
Message-ID: <h34lml$6fv$1@ger.gmane.org>
Mime-Version: 1.0
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
X-Complaints-To: usenet@ger.gmane.org
X-Gmane-NNTP-Posting-Host: lara.cc.fer.hr
User-Agent: Thunderbird 2.0.0.21 (X11/20090615)
Sender: news <news@ger.gmane.org>
Subject: glabel and real disk IDs
X-BeenThere: freebsd-geom@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: GEOM-specific discussions and implementations
	<freebsd-geom.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-geom>,
	<mailto:freebsd-geom-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-geom>
List-Post: <mailto:freebsd-geom@freebsd.org>
List-Help: <mailto:freebsd-geom-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-geom>,
	<mailto:freebsd-geom-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Thu, 09 Jul 2009 11:53:09 -0000

Hi,

I've been working with glabels for a time and just remembered that ATA 
(ad) drives do in fact export the drive ID, for example:

# diskinfo -v ad4
ad4
         512             # sectorsize
         320072933376    # mediasize in bytes (298G)
         625142448       # mediasize in sectors
         620181          # Cylinders according to firmware.
         16              # Heads according to firmware.
         63              # Sectors according to firmware.
         ad:9QF4H15Y     # Disk ident.

# diskinfo -v ad6
ad6
         512             # sectorsize
         320072933376    # mediasize in bytes (298G)
         625142448       # mediasize in sectors
         620181          # Cylinders according to firmware.
         16              # Heads according to firmware.
         63              # Sectors according to firmware.
         ad:9QF4EP7A     # Disk ident.

# diskinfo -v ad8
ad8
         512             # sectorsize
         320072933376    # mediasize in bytes (298G)
         625142448       # mediasize in sectors
         620181          # Cylinders according to firmware.
         16              # Heads according to firmware.
         63              # Sectors according to firmware.
         ad:9QF4H16L     # Disk ident.

I don't think it would be hard to add a label parser to gather this 
information and export it as a label.

The purpose of this would be to have a unique disk ID without explicitly 
setting a label (e.g. as is commonly advised for ZFS and drive swapping).

Any objections?