From owner-freebsd-sysinstall@FreeBSD.ORG Sun May 25 16:54:06 2014 Return-Path: Delivered-To: freebsd-sysinstall@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 4BF05E00; Sun, 25 May 2014 16:54:06 +0000 (UTC) Received: from i3mail.icecube.wisc.edu (i3mail.icecube.wisc.edu [128.104.255.23]) by mx1.freebsd.org (Postfix) with ESMTP id 1B32C2EFD; Sun, 25 May 2014 16:54:05 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by i3mail.icecube.wisc.edu (Postfix) with ESMTP id 8A8A638061; Sun, 25 May 2014 11:54:05 -0500 (CDT) X-Virus-Scanned: amavisd-new at icecube.wisc.edu Received: from i3mail.icecube.wisc.edu ([127.0.0.1]) by localhost (i3mail.icecube.wisc.edu [127.0.0.1]) (amavisd-new, port 10030) with ESMTP id mdgZirQobrki; Sun, 25 May 2014 11:54:05 -0500 (CDT) Received: from comporellon.tachypleus.net (polaris.tachypleus.net [75.101.50.44]) by i3mail.icecube.wisc.edu (Postfix) with ESMTPSA id 292EF3805E; Sun, 25 May 2014 11:54:05 -0500 (CDT) Message-ID: <5382202C.2010202@freebsd.org> Date: Sun, 25 May 2014 09:54:04 -0700 From: Nathan Whitehorn User-Agent: Mozilla/5.0 (X11; FreeBSD amd64; rv:24.0) Gecko/20100101 Thunderbird/24.5.0 MIME-Version: 1.0 To: Allan Jude , freebsd-sysinstall@freebsd.org Subject: Re: bin/164281: bsdinstall(8): please allow sysinstall as installer option References: <201404151630.s3FGU0Zg026166@freefall.freebsd.org> <012501cf5f1f$c5e7c740$51b755c0$@FreeBSD.org> <5358223B.1090408@gmail.com> <535827AC.3040503@allanjude.com> <53582CC4.2080808@freebsd.org> <53583D5C.5020506@pix.net> <53583DB8.1080905@freebsd.org> <20140423230210.GA20429@pix.net> <538219DA.3040702@freebsd.org> <53821B1F.8000509@freebsd.org> <53821DC6.60701@freebsd.org> <53821E75.10000@freebsd.org> In-Reply-To: <53821E75.10000@freebsd.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-BeenThere: freebsd-sysinstall@freebsd.org X-Mailman-Version: 2.1.18 Precedence: list List-Id: Sysinstall Work List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 25 May 2014 16:54:06 -0000 On 05/25/14 09:46, Allan Jude wrote: > On 2014-05-25 12:43, Nathan Whitehorn wrote: >> On 05/25/14 09:32, Allan Jude wrote: >>> On 2014-05-25 12:27, Nathan Whitehorn wrote: >>>> I'm (finally) integrating these patches now. Could you remind me what >>>> the point of the gnop is? I'm not sure I get it. >>>> -Nathan >>> The 'gnop -S 4096 ' makes a virtual device that has a sector >>> size of 4096 bytes. This causes ZFS to set ashift=12 even for devices >>> that mis-advertise (lie about) their sector size. There is no real harm >>> in using 4k sectors on a 512b sector device, but using 512b sectors on a >>> 4k device will cause write amplification (read-modify-write) since the >>> device will have to deal with it as a partial block update. >> I think our ATA code mostly has this under control at this point. >> >>> Additionally, the sector size can only be set at pool creation time, >>> even if you have have 512b sector devices, you'll want to create your >>> pool as 4k, so that in the future when you add additional devices, or >>> replace failed devices, the 4k sector devices will be supported. ZFS >>> complains loudly when you try to add mis-matched sector size devices to >>> a pool. >>> >>> >> This is a good reason, even if the circumstances behind it are stupid. >> Is there really no way to handle this besides gnop? Can't we just fix ZFS? >> -Nathan >> _______________________________________________ >> freebsd-sysinstall@freebsd.org mailing list >> http://lists.freebsd.org/mailman/listinfo/freebsd-sysinstall >> To unsubscribe, send any mail to >> "freebsd-sysinstall-unsubscribe@freebsd.org" > Linux added an explicit option to the zpool, so you can just do: > > zpool create -o ashift=12 mypool mirror disk1 disk2 > > There was some discussion about this in the OpenZFS group, but it was > usually cited as a reason why there was a need to for OpenZFS, to keep > the Linux version from diverging and adding a bunch of non-standard options. > > I am not sure what the best option is. The gnop is only required while > the pool is being created, it doesn't need to be re-created in order to > import the pool etc, it is just to trick ZFS the first time. > If it's really just needed at creation time, the best way forward seems pretty clearly to be the -o ashift one. Let's see if we can do that. -Nathan