Date: Wed, 25 May 2011 08:24:40 -0700 From: Marcel Moolenaar <xcllnt@mac.com> To: Andriy Gapon <avg@freebsd.org> Cc: "Andrey V. Elsukov" <bu7cher@yandex.ru>, Warner Losh <imp@bsdimp.com>, freebsd-geom@FreeBSD.org Subject: Re: [RFC] Remove requirement of alignment to track from MBR scheme Message-ID: <BF2C4EFE-C43D-4AB2-BBF4-9D0F92B112A9@mac.com> In-Reply-To: <4DDD1C56.70706@FreeBSD.org> References: <4DDA2F0B.2040203@yandex.ru> <D75B2856-D9D8-4BA3-BC54-8258610CEA06@xcllnt.net> <9ED563AB-7B35-40F4-A33E-015317858401@bsdimp.com> <4DDB5375.6050004@FreeBSD.org> <D7C4124D-A690-4960-B141-594C7E2BE792@mac.com> <2FCA1E3C-E11C-46C9-A41B-E5DF4D8BA1FC@bsdimp.com> <9B250685-62F2-4AF7-BDCC-D176FA3C6FCD@mac.com> <4DDD1C56.70706@FreeBSD.org>
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On May 25, 2011, at 8:12 AM, Andriy Gapon wrote: > on 24/05/2011 21:12 Marcel Moolenaar said the following: >> With respect to the creation: >> >> Since out synthesized geometry is not necessarily the same >> as other OSes, we could opt to synthesize a geometry that >> has a track size (= sectors/track) that is a multiple of 8 >> (to play nice with 4K sectors), and/or take the stripe >> size of the underlying GEOM into account. This fundamentally >> doesn't change a thing for MBR, but has the side effect of >> achieving some of the goals *and* automatically works for >> EBR as well. >> >> Thus: rather than hack MBR and forgetting about EBR and other >> schemes, maybe we only have to tweak the geometry synthesis >> to give people what they want without going over board. > > I don't think that currently we do synthesize any geometry in kernel. > I think that we just whatever BIOS/firmware/etc provides to us in some way. Yes, we do. gpart makes sure that there's always a geometry and it adjusts the geometry based on information obtained from schemes. The geometry given by geom_disk (= ad or da) is typically the starting point. md does not have geometry information, causing certain tools to work less well. -- Marcel Moolenaar xcllnt@mac.com
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