From mboxrd@z Thu Jan 1 00:00:00 1970 From: "H. Peter Anvin" Subject: Re: ATA 4 KiB sector issues. Date: Mon, 08 Mar 2010 10:50:14 -0800 Message-ID: <4B9546E6.6050006@zytor.com> References: <4B947393.2050002@kernel.org> <1268031640.4389.11.camel@mulgrave.site> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Return-path: Received: from terminus.zytor.com ([198.137.202.10]:50144 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754470Ab0CHSup (ORCPT ); Mon, 8 Mar 2010 13:50:45 -0500 In-Reply-To: Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: "Martin K. Petersen" Cc: James Bottomley , Tejun Heo , "linux-ide@vger.kernel.org" , lkml , Daniel Taylor , Jeff Garzik , Mark Lord , tytso@mit.edu, hirofumi@mail.parknet.co.jp, Andrew Morton , Alan Cox , irtiger@gmail.com, Matthew Wilcox , aschnell@suse.de, knikanth@suse.de, jdelvare@suse.de On 03/08/2010 07:41 AM, Martin K. Petersen wrote: >>>>>> "Martin" == Martin K Petersen writes: > >>>>>> "Martin" == Martin K Petersen writes: > Martin> There are 4 KB LBS SSDs out there but in general the industry is > Martin> sticking to ATA for local boot. > > Martin> Thus implying that ATA doesn't support 4 KB LBS, just that > Martin> people stick to the tried-and-true 512. > > *sigh* I haven't had my breakfast tea yet... > > What I meant to say was that I know ATA supports 4 KB LBS and that > nobody appears to care about it. > Well, apparently Western Digital are looking at it for USB drives due to XP compatibility requirements -- those presumably are ATA internally and use a USB-ATA bridge. On the flipside, though, there really is very little net benefit to 4K as opposed to 512 byte logical sectors: the additional protocol overhead is relatively minimal, and as long as writes are aligned full blocks, there shouldn't be any additional overhead on either the OS or the drive side. On the plus side, you get full compatibility with the existing software stack. The equation really seems rather simple. -hpa