From owner-freebsd-questions@FreeBSD.ORG Sun Dec 4 03:37:15 2011 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id A30781065672 for ; Sun, 4 Dec 2011 03:37:15 +0000 (UTC) (envelope-from perryh@pluto.rain.com) Received: from agora.rdrop.com (agora.rdrop.com [IPv6:2607:f678:1010::34]) by mx1.freebsd.org (Postfix) with ESMTP id 80ABB8FC0C for ; Sun, 4 Dec 2011 03:37:15 +0000 (UTC) Received: from agora.rdrop.com (66@localhost [127.0.0.1]) by agora.rdrop.com (8.13.1/8.12.7) with ESMTP id pB43bBgP034940 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NOT); Sat, 3 Dec 2011 19:37:12 -0800 (PST) (envelope-from perryh@pluto.rain.com) Received: (from uucp@localhost) by agora.rdrop.com (8.13.1/8.12.9/Submit) with UUCP id pB43bBEC034939; Sat, 3 Dec 2011 19:37:11 -0800 (PST) Received: from fbsd81 ([192.168.200.81]) by pluto.rain.com (4.1/SMI-4.1-pluto-M2060407) id AA03189; Sat, 3 Dec 11 19:28:58 PST Date: Sun, 04 Dec 2011 02:28:24 -0800 From: perryh@pluto.rain.com To: cyberleo@cyberleo.net Message-Id: <4edb4b48.LvOhZvvsP1inJeps%perryh@pluto.rain.com> References: <4ED98E9F.9010401@midsummerdream.org> <4EDA489B.9060503@midsummerdream.org> <4EDA56A3.6090108@cyberleo.net> In-Reply-To: <4EDA56A3.6090108@cyberleo.net> User-Agent: nail 11.25 7/29/05 Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: ryallsd@gmail.com, freebsd-questions@freebsd.org, lists@midsummerdream.org Subject: Re: AHCI driver and static device names X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 04 Dec 2011 03:37:15 -0000 CyberLeo Kitsana wrote: > You cannot combine GPT with glabel (or any other geom class > that writes data to the first or last 34 sectors of a disk, > like gmirror) due to layout conflicts. This is overstated. Since a GPT ordinarily is intended to be booted from, and so must be recognized by the BIOS, it must be written directly on the actual drive -- the "rank 1 provider" in GEOM terms -- because that is the only way for the GPT metadata to be located where the BIOS expects to find it (at both the beginning and the end of the drive). It is, however, possible to combine GPT with gmirror, gjournal, etc. by using GPT partitions, rather than drives, as providers for the other geoms. For example, create a mirror from ad0p1 and ad2p1 rather than from ad0 and ad2. Similarly, it "should" be possible to glabel a GPT partition -- although this seems unlikely to be useful in practice since GPT provides its own labelling scheme.