From owner-freebsd-questions@FreeBSD.ORG Mon Oct 19 14:26:51 2009 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 B18FF106566C for ; Mon, 19 Oct 2009 14:26:51 +0000 (UTC) (envelope-from af.gourmet@videotron.ca) Received: from relais.videotron.ca (relais.videotron.ca [24.201.245.36]) by mx1.freebsd.org (Postfix) with ESMTP id 8919A8FC0C for ; Mon, 19 Oct 2009 14:26:51 +0000 (UTC) MIME-version: 1.0 Content-transfer-encoding: 7BIT Content-type: text/plain; charset=UTF-8 Received: from [192.168.0.51] ([96.21.103.185]) by VL-MH-MR001.ip.videotron.ca (Sun Java(tm) System Messaging Server 6.3-4.01 (built Aug 3 2007; 32bit)) with ESMTP id <0KRR000HHMSQ3U60@VL-MH-MR001.ip.videotron.ca> for freebsd-questions@freebsd.org; Mon, 19 Oct 2009 10:26:50 -0400 (EDT) Message-id: <4ADC772F.3060303@videotron.ca> Date: Mon, 19 Oct 2009 10:26:55 -0400 From: PJ User-Agent: Thunderbird 2.0.0.23 (Windows/20090812) To: Johan Hendriks References: <4ADC6D89.10600@videotron.ca> <57200BF94E69E54880C9BB1AF714BBCBA57086@w2003s01.double-l.local> In-reply-to: <57200BF94E69E54880C9BB1AF714BBCBA57086@w2003s01.double-l.local> Cc: Polytropon , freebsd-questions@freebsd.org Subject: Re: glabel clarification 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: Mon, 19 Oct 2009 14:26:51 -0000 Johan Hendriks wrote: >> I understood that labeling a disk with glabel would permit the disk to >> be switched to another system and booting from that disk would not >> require other manupulations than adjusting network configuration, >> > samba, > >> rc.conf and a few others.. >> But what if there is already a disk on the system with the identical >> labels in /dev/label/ ? >> I understood that whatever the actual disk might be (ad4, ad12, >> ad1...)would be irrelevant? >> It would appear that the actual booting goes according to the label; >> > so, > >> if there are duplicate labels the boot will not necessarily be from the >> newly installed disk if there is another disk with duplicate glabel >> > labels? > >> So doing a glabel seems superfluous... >> What then is the real purpose of glabel, since the boot process seems >> > to > >> need a unique identifier? >> > > Switching between machines is not what labels are for.(enlighten me if > it is) > As far as understand, it makes switching the drive in the same machine > easier. > It does not matter if labels are used, that the device is seen as > /dev/ad0 or /dev/ad{x}. > This makes adding and replacing disk much easier. > Sometimes the disk numbers change when removing raid controllers or > other hardware. > Yes, this is true and that is why I thought that glabel would work; I am trying to set up my computers with identical clones that I can update with changes on the master machine from time to time and thus prevent data loss in case of problems. So I use ad12 as the main system; if it were to crash I would then boot from ad6 which is identical. But the /etc/fstab is identical in both machines. So if I boot from ad6, I will get booted from ad12 ... so that doesn't work. It looks like we need an unique identifier for each disk.