From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Tue, 28 Aug 2001 08:23:15 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Tue, 28 Aug 2001 08:23:05 -0400 Received: from kweetal.tue.nl ([131.155.2.7]:7213 "EHLO kweetal.tue.nl") by vger.kernel.org with ESMTP id ; Tue, 28 Aug 2001 08:22:48 -0400 Message-ID: <20010828142315.A20775@win.tue.nl> Date: Tue, 28 Aug 2001 14:23:15 +0200 From: Guest section DW To: nick@guardiandigital.com, linux-kernel@vger.kernel.org Subject: Re: Determining maximum partition size on a hard disk In-Reply-To: <3B82BCCB.377BCC4@guardiandigital.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Mailer: Mutt 0.93i In-Reply-To: <3B82BCCB.377BCC4@guardiandigital.com>; from Nick DeClario on Tue, Aug 21, 2001 at 03:55:55PM -0400 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Aug 21, 2001 at 03:55:55PM -0400, Nick DeClario wrote: > I am trying to calculate the maximum size a partition can be on a hard > drive and I ran into some problems I don't fully understand. > > First I found that the maximum size of the drive Linux reports is not > the maximum size I get when I calculate it from the drives geometry. > Secondly, the total drive space reported by linux is not the amount > available for the maximum partition. > > For example, I have a 4.3Gb disk. The drives geometry is 525 cylinders, > 255 heads and 63 sectors (525 * 255 * 63 * 512 = 4318272000 or > 4.318Gb). > > This is an IDE disk so I found in /proc/ide/hdx/capacity a block size > 8439184, which when divided by 2048 is 4120.7, ~200Mb less than what I > calculated as the disk size. I don't know why you would want to divide by 2048. Multiply by 512 and find 512*8439184 = 4320862208 bytes. Since that is more than you thought you had, be happy. > I assume that the difference between the maximum size that linux reports > and the maximum partition size is due to linux leaving room for a MBR No. There are rounding differences. The disk capacity is not an integral number of cylinders and you lose if you insist on alignment. Find a lot of details in the Large Disk Howto. > I thought maybe Linux set 1MB=1000k but that doesn't seem to case. Well, 1 M = 1000 k by definition of the SI system of units. This has nothing to do with Linux. But if you are confused about units, just compute in bytes.