From owner-freebsd-hackers@FreeBSD.ORG Sun Jun 1 16:00:23 2014 Return-Path: Delivered-To: freebsd-hackers@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [8.8.178.115]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 51FA1E9B; Sun, 1 Jun 2014 16:00:23 +0000 (UTC) Received: from smtp1.multiplay.co.uk (smtp1.multiplay.co.uk [85.236.96.35]) by mx1.freebsd.org (Postfix) with ESMTP id 13C2627C0; Sun, 1 Jun 2014 16:00:22 +0000 (UTC) Received: by smtp1.multiplay.co.uk (Postfix, from userid 65534) id 4E46120E7088C; Sun, 1 Jun 2014 16:00:22 +0000 (UTC) X-Spam-Checker-Version: SpamAssassin 3.3.1 (2010-03-16) on smtp1.multiplay.co.uk X-Spam-Level: ** X-Spam-Status: No, score=2.0 required=8.0 tests=AWL,BAYES_00,DOS_OE_TO_MX, FSL_HELO_NON_FQDN_1,HELO_NO_DOMAIN,RDNS_DYNAMIC autolearn=no version=3.3.1 Received: from r2d2 (82-69-141-170.dsl.in-addr.zen.co.uk [82.69.141.170]) by smtp1.multiplay.co.uk (Postfix) with ESMTPS id 1BDE020E70886; Sun, 1 Jun 2014 16:00:17 +0000 (UTC) Message-ID: <1DB2D63312CE439A96B23EAADFA9436E@multiplay.co.uk> From: "Steven Hartland" To: "Nathan Whitehorn" , , References: <20140601004242.GA97224@bewilderbeast.blackhelicopters.org> <3D6974D83AE9495E890D9F3CA654FA94@multiplay.co.uk> <538B4CEF.2030801@freebsd.org> Subject: Re: fdisk(8) vs gpart(8), and gnop Date: Sun, 1 Jun 2014 17:00:21 +0100 MIME-Version: 1.0 Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=response Content-Transfer-Encoding: 7bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 6.00.2900.5931 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.6157 X-BeenThere: freebsd-hackers@freebsd.org X-Mailman-Version: 2.1.18 Precedence: list List-Id: Technical Discussions relating to FreeBSD List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 01 Jun 2014 16:00:23 -0000 ----- Original Message ----- From: "Nathan Whitehorn" To: ; Sent: Sunday, June 01, 2014 4:55 PM Subject: Re: fdisk(8) vs gpart(8), and gnop > On 06/01/14 08:52, Steven Hartland wrote: >> ----- Original Message ----- From: "Mark Felder" >> >>> On May 31, 2014, at 20:57, Freddie Cash wrote: >>> >>>> There's a sysctl where you can set the minimum ashift for zfs. Then you >>>> never need to use gnop. >>>> >>>> I believe it's part of 10.0? >>> >>> I've not seen this yet. What we need is to port the ability to set >>> ashift at pool creation time: >>> >>> $ zpool create -o ashift=12 tank mirror disk1 disk2 mirror disk3 disk4 >>> >>> I believe the Linux zfs port has this functionality now, but we still >>> do not. >> >> We don't have that direct option yet but you can achieve the >> same thing by setting: vfs.zfs.min_auto_ashift=12 >> > Does anyone have any objections to me changing this default, right now, > today? > -Nathan I think you will get some objections to that, as it can have quite an impact on the performance for disks which are 512, due to the increased overhead of transfering 4k when only 512 is really required. This has a more dramatic impact on RAIDZx due too. Personally we run a custom kernel on our machines which has just this change in it to ensure capability with future disks, so I can confirm it does indeed have the desired effect :) Regards Steve