From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: util-linux-owner@vger.kernel.org Received: from mail-pd0-f179.google.com ([209.85.192.179]:48410 "EHLO mail-pd0-f179.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S933959AbaJ2Qkw (ORCPT ); Wed, 29 Oct 2014 12:40:52 -0400 Received: by mail-pd0-f179.google.com with SMTP id g10so3294138pdj.38 for ; Wed, 29 Oct 2014 09:40:52 -0700 (PDT) Received: from [192.168.1.2] ([117.208.69.53]) by mx.google.com with ESMTPSA id dx10sm4819106pab.38.2014.10.29.09.40.49 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Wed, 29 Oct 2014 09:40:51 -0700 (PDT) Message-ID: <5451187A.3000304@gmail.com> Date: Wed, 29 Oct 2014 22:10:26 +0530 From: dE MIME-Version: 1.0 To: util-linux@vger.kernel.org Subject: Re: fdisk and 2048 sectors obsession. References: <544E923E.6050406@gmail.com> <20141028075308.GI10134@x2.net.home> <544FAE07.6080605@gmail.com> <20141028153557.GA20378@thunk.org> In-Reply-To: <20141028153557.GA20378@thunk.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Sender: util-linux-owner@vger.kernel.org List-ID: On 10/28/14 21:05, Theodore Ts'o wrote: > On Tue, Oct 28, 2014 at 08:23:59PM +0530, dE wrote: >>> Not only that. It was an explicit request from IDEMA. The disk drive and >>> RAID vendors asked all operating system vendors to ensure 1MB alignment >>> by default. >>> >> Ok, it's an IDEMA recommendation. That's why. > One additional reason why it's a good idea is for better compatibility > with drive-managed or host-aware SMR (Shingled Magnetic Recording) > disks, it's a really good idea if partitions are aligned on 256 MiB > boundaries. > > And in the future, the hard drive vendors hope to promulgate 32k or > 64k native sector size. If we adopted the suggestion to align new > partitions at 4k after the MBR, it would be disastrous for SMR disks > (some of which will be shipping soon, or may be shipping already but > you might know it, especially for some high-capacity USB attached > storage), and for these larger sector disks. > > Or if you are using very low-end flash (i.e., on SD cards) which have > a very primitive FTL, if the partitions aren't aligned on the erase > block, you will also have terrible performance --- and this is true > today. > > Given the painful history of how long it took to get OS vendors to > move off of a sector 63 offset (a decade, thanks to Windows XP), it's > not surprising IDEMA has requested that all OS vendors use a 1MB > alignment for partitions going forward. > > So I don't think we want to change the default. If you're so hard up > for space that clawing back that extra 1020k with of disks on a 2T or > 6T disk is significant, you can manually adjust the starting offset of > the partition. But I really don't think it's worth it, at least for > myself.... > > Cheers, > > - Ted Thanks for all the answers everyone! Now I get the point. This conversation will get a lot of hits.