From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S271086AbTGQPuo (ORCPT ); Thu, 17 Jul 2003 11:50:44 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S271108AbTGQPuo (ORCPT ); Thu, 17 Jul 2003 11:50:44 -0400 Received: from kweetal.tue.nl ([131.155.3.6]:34062 "EHLO kweetal.tue.nl") by vger.kernel.org with ESMTP id S271086AbTGQPsf (ORCPT ); Thu, 17 Jul 2003 11:48:35 -0400 Date: Thu, 17 Jul 2003 18:03:28 +0200 From: Andries Brouwer To: Jeff Garzik Cc: Alan Cox , Walt H , arjanv@redhat.com, Linux Kernel Mailing List , davzaffiro@tasking.nl Subject: Re: [PATCH] pdcraid and weird IDE geometry Message-ID: <20030717180328.A2467@pclin040.win.tue.nl> References: <3F160965.7060403@comcast.net> <1058431742.5775.0.camel@laptop.fenrus.com> <3F16B49E.8070901@comcast.net> <1058453918.9055.12.camel@dhcp22.swansea.linux.org.uk> <3F16C1F3.40206@pobox.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.2.5.1i In-Reply-To: <3F16C1F3.40206@pobox.com>; from jgarzik@pobox.com on Thu, Jul 17, 2003 at 11:34:11AM -0400 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Jul 17, 2003 at 11:34:11AM -0400, Jeff Garzik wrote: > Can't you fix the geometry from fdisk expert mode? > > I've done that several times before, when otherwise like-sized disks > appeared with vastly different geometry. It is easiest to think that it is meaningless what you say (in this case). A disk does not have a geometry, and moreover you cannot change it with fdisk. However, under some circumstances, some kernels will guess a (translated) geometry from a DOS-type partition table, so it is true that under some kernel versions you can use fdisk to change the kernel's ideas about disk geometry. A very fragile activity. [Moreover, there are several kinds of geometry, and the present authors of ide-disk.c conveniently confused them all. Concerning pdcraid, I don't know for which of the possible ideas of geometry it is true that one needs the first sector of the last cylinder.] Andries