From owner-freebsd-current@FreeBSD.ORG Sat Mar 18 14:59:26 2006 Return-Path: X-Original-To: freebsd-current@freebsd.org Delivered-To: freebsd-current@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 1BB0416A400 for ; Sat, 18 Mar 2006 14:59:26 +0000 (UTC) (envelope-from dmitry@atlantis.dp.ua) Received: from postman.atlantis.dp.ua (postman.atlantis.dp.ua [193.108.47.1]) by mx1.FreeBSD.org (Postfix) with ESMTP id 493CD43D45 for ; Sat, 18 Mar 2006 14:59:24 +0000 (GMT) (envelope-from dmitry@atlantis.dp.ua) Received: from smtp.atlantis.dp.ua (smtp.atlantis.dp.ua [193.108.46.231]) by postman.atlantis.dp.ua (8.13.1/8.13.1) with ESMTP id k2IExDDj044225; Sat, 18 Mar 2006 16:59:13 +0200 (EET) (envelope-from dmitry@atlantis.dp.ua) Date: Sat, 18 Mar 2006 16:59:13 +0200 (EET) From: Dmitry Pryanishnikov To: Jos Backus In-Reply-To: <20060318050116.GA19952@lizzy.catnook.local> Message-ID: <20060318162413.K32225@atlantis.atlantis.dp.ua> References: <20060317012428.N52721@atlantis.atlantis.dp.ua> <863bhh3y05.fsf@xps.des.no> <20060317174743.GA13507@lizzy.catnook.local> <20060317213430.R31244@atlantis.atlantis.dp.ua> <20060317204704.GA16269@lizzy.catnook.local> <20060318032023.K40573@atlantis.atlantis.dp.ua> <20060318050116.GA19952@lizzy.catnook.local> MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed Cc: freebsd-current@freebsd.org Subject: Re: [patch] NetBSD disklabel support for geom_bsd X-BeenThere: freebsd-current@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Discussions about the use of FreeBSD-current List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 18 Mar 2006 14:59:26 -0000 Hello! On Fri, 17 Mar 2006, Jos Backus wrote: >> Well, as I wrote in my previuos letter, it's my mistake that FreeBSD >> uses slice-relative offsets while NetBSD uses absolute offsets. Actually, >> both systems use absolute offsets, and offset conversion isn't required >> (but just accidently happens harmless). > > I thought they were relative too. So this means one cannot move either FreeBSD And when disklabel shows contents of label, it (or, maybe, geom_bsd nowadays) auto-converts absolute media offsets to slice-relative. It was another source of my confusion. > or NetBSD partitions without modifying the label, requiring the moving tool > (such as PM) having to understand the label format. Seems like a downside to > me. Yes, exactly, but it's not something that we can easily change: it seems that all *BSD's do it in this way. RELENG_4 auto-converts offsets to slice-relative when you read label off the slice. I suppose that it should allow transferring slice image to "dangerously dedicated" (sliceless) media of the same size, and getting valid disklabel as a result. Nice idea, but in some situations it can hurt. Once I had to remotely replace Linux with FreeBSD on some co-location. I've prepared disk slice for FreeBSD at colo, locally created the same (as at colo) HDD layout on my disk, locally installed FreeBSD-4.11, dd'ed slice contents to a file, transferred it to the colo, dd'ed it it that slice, switched active partition to this slice, rebooted the machine. Machine didn't come up! It was due to the label auto-conversion on fly: when I've dd'ed slice to a file on local FreeBSD system, absolute offsets were converted to relative. Of course, Linux at colo didn't change them back to absolute ;) Sincerely, Dmitry -- Atlantis ISP, System Administrator e-mail: dmitry@atlantis.dp.ua nic-hdl: LYNX-RIPE