From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ted Ts'o Subject: Re: [PATCH][RFC]ext4 on 4k-sector drives without read-modify-write support Date: Mon, 28 Feb 2011 16:05:41 -0500 Message-ID: <20110228210541.GF28617@thunk.org> References: <20110228180925.GA28617@thunk.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Jeff Moyer , Ibragimov Rinat , linux-fsdevel@vger.kernel.org To: "Martin K. Petersen" Return-path: Received: from li9-11.members.linode.com ([67.18.176.11]:48966 "EHLO test.thunk.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754705Ab1B1VFs (ORCPT ); Mon, 28 Feb 2011 16:05:48 -0500 Content-Disposition: inline In-Reply-To: Sender: linux-fsdevel-owner@vger.kernel.org List-ID: On Mon, Feb 28, 2011 at 03:19:21PM -0500, Martin K. Petersen wrote: > Kind of, yes. But that involves teaching every ATA driver in $LEGACY_OS > about 4KB logical blocks. There is little value is switching to 4KB > logical blocks in the first place. So the claim is that it is easier to > stick with 512-byte addressing, leave the I/O stack intact, and require > the filesystem to always issue aligned units of 4KB. > > That saves the drive vendors from implementing RMW logic and puts the > burden on us. Perfect deal. So it there a reliable way to detect that disk drives that don't have the Read-Modify-Write logic? If that can be reflected up the I/O layer I can have mke2fs enforce that restriction, which currently we only enforce if the logical blocksize is 4k. - Ted