From owner-freebsd-geom@FreeBSD.ORG Tue May 24 09:23:03 2011 Return-Path: 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 9105D10657D4 for ; Tue, 24 May 2011 09:23:03 +0000 (UTC) (envelope-from avg@FreeBSD.org) Received: from citadel.icyb.net.ua (citadel.icyb.net.ua [212.40.38.140]) by mx1.freebsd.org (Postfix) with ESMTP id D57408FC15 for ; Tue, 24 May 2011 09:23:02 +0000 (UTC) Received: from porto.topspin.kiev.ua (porto-e.starpoint.kiev.ua [212.40.38.100]) by citadel.icyb.net.ua (8.8.8p3/ICyb-2.3exp) with ESMTP id MAA27953; Tue, 24 May 2011 12:22:48 +0300 (EEST) (envelope-from avg@FreeBSD.org) Received: from localhost.topspin.kiev.ua ([127.0.0.1]) by porto.topspin.kiev.ua with esmtp (Exim 4.34 (FreeBSD)) id 1QOnpA-0006iu-9n; Tue, 24 May 2011 12:22:48 +0300 Message-ID: <4DDB78E7.2070301@FreeBSD.org> Date: Tue, 24 May 2011 12:22:47 +0300 From: Andriy Gapon User-Agent: Mozilla/5.0 (X11; U; FreeBSD amd64; en-US; rv:1.9.2.17) Gecko/20110503 Lightning/1.0b2 Thunderbird/3.1.10 MIME-Version: 1.0 To: "Andrey V. Elsukov" References: <4DDA2F0B.2040203@yandex.ru> <9ED563AB-7B35-40F4-A33E-015317858401@bsdimp.com> <4DDB5375.6050004@FreeBSD.org> <4DDB74B2.702@yandex.ru> In-Reply-To: <4DDB74B2.702@yandex.ru> X-Enigmail-Version: 1.1.2 Content-Type: text/plain; charset=KOI8-R Content-Transfer-Encoding: 7bit Cc: Marcel Moolenaar , Warner Losh , freebsd-geom@FreeBSD.org Subject: Re: [RFC] Remove requirement of alignment to track from MBR scheme X-BeenThere: freebsd-geom@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: GEOM-specific discussions and implementations List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 24 May 2011 09:23:03 -0000 on 24/05/2011 12:04 Andrey V. Elsukov said the following: > There are several operations which can/should be changed: > 1. MBR detection. All users want keep their partitions accessible. > But with r221788 it is now problematic. I can revert r221788, but for > me it seems right and instead reverting MBR support should be changed: > a) table->gpt_last should not be aligned to track boundary; > b) table->gpt_first can be aligned to track for compatibility, but > if there is already some partition starts from inside first > track, table->gpt_first should be set to 1. I think that we should completely ignore anything and everything CHS in our _validations_ (should not even warn). Words/notions "track", "cylinder", "head" should just disappear from source code. On other points - I agree with you. > 2. MBR creating. > a) table->gpt_last should not be aligned to track boundary; > b) table->gpt_first can be aligned to track for compatibility. > > 3. Creating partitions. Users should choose alignment method, not the kernel. > and they can do it: > Align to 4k: > # gpart add -t freebsd -a 4k -s 5g ada0 > > Align according to disk geometry: > # gpart add -t freebsd -g -s 5g ada0 > > So, patch is here: > http://people.freebsd.org/~ae/mbr_geometry.diff > > Examples: > > # gpart create -s mbr md0 > md0 created > # gpart show md0 > => 63 4294967232 md0 MBR (5.5T) > 63 4294967232 - free - (2T) > > # gpart add -t freebsd -s 10g -a 4k md0 > md0s1 added > # gpart show md0 > => 63 4294967232 md0 MBR (5.5T) > 63 1 - free - (512B) > 64 20971520 1 freebsd (10G) > 20971584 4273995711 - free - (2T) > > # gpart add -t freebsd -s 10g -g md0 > md0s2 added > # gpart show md0 > => 63 4294967232 md0 MBR (5.5T) > 63 1 - free - (512B) > 64 20971520 1 freebsd (10G) > 20971584 45 - free - (22k) > 20971629 20971503 2 freebsd (10G) > 41943132 4253024163 - free - (2T) > -- Andriy Gapon