From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Martin K. Petersen" Subject: Re: ATA support for 4k sector size Date: Wed, 25 Feb 2009 22:05:30 -0500 Message-ID: References: <1235600698-6446-1-git-send-email-matthew@wil.cx> <49A5CBF7.9000501@zytor.com> <20090226025043.GJ1363@mit.edu> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from acsinet11.oracle.com ([141.146.126.233]:38106 "EHLO acsinet11.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752600AbZBZDGi (ORCPT ); Wed, 25 Feb 2009 22:06:38 -0500 In-Reply-To: <20090226025043.GJ1363@mit.edu> (Theodore Tso's message of "Wed\, 25 Feb 2009 21\:50\:43 -0500") Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: Theodore Tso Cc: "Martin K. Petersen" , "H. Peter Anvin" , Matthew Wilcox , linux-ide@vger.kernel.org, linux-kernel@vger.kernel.org, sandeen@redhat.com >>>>> "Ted" == Theodore Tso writes: >> Because of 63-sector legacy problems a bunch of ATA vendors will >> initially ship 512/4096 drives that are not naturally aligned. >> I.e. logical sector 63 will be aligned on a 4KB hardware sector >> boundary to overcome the misaligned default partitioning. >> Ted> Are we *sure* that this is what they plan to be doing? I have asked my contacts to verify. That was the plan as of last October. Ted> Is there a way we can query the hardware to find out for sure what Ted> drives are doing what? Yep. And with my patches the appropriate alignment is exposed in sysfs for each block device. Hardware workarounds for DOS partition table brain damage have existed for a long time. On a lot of RAID arrays you have to pick a LUN personality. And by choosing DOS/Windows/Linux you often align sector 63 to the internal RAID chunk size. I'm working with several RAID vendors to make sure they set the right alignment offset when they do that. That isn't currently the case. The alignment knobs only recently made their appearance in the spec to accommodate the 4KB sector transition. Ted> I'll note that Vista starts all new partitions at the 1MB boundary, Ted> so its filesystems will be naturally aligned. Maybe. See above. -- Martin K. Petersen Oracle Linux Engineering