From owner-freebsd-sysinstall@FreeBSD.ORG Sun May 25 16:43:53 2014 Return-Path: Delivered-To: freebsd-sysinstall@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits)) (No client certificate requested) by hub.freebsd.org (Postfix) with ESMTPS id 0152AC9D; Sun, 25 May 2014 16:43:53 +0000 (UTC) Received: from i3mail.icecube.wisc.edu (i3mail.icecube.wisc.edu [128.104.255.23]) by mx1.freebsd.org (Postfix) with ESMTP id C44542E52; Sun, 25 May 2014 16:43:52 +0000 (UTC) Received: from localhost (localhost [127.0.0.1]) by i3mail.icecube.wisc.edu (Postfix) with ESMTP id 1408E3805B; Sun, 25 May 2014 11:43:52 -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 RL0V87QtDRGa; Sun, 25 May 2014 11:43:52 -0500 (CDT) Received: from comporellon.tachypleus.net (polaris.tachypleus.net [75.101.50.44]) by i3mail.icecube.wisc.edu (Postfix) with ESMTPSA id 7836B38059; Sun, 25 May 2014 11:43:51 -0500 (CDT) Message-ID: <53821DC6.60701@freebsd.org> Date: Sun, 25 May 2014 09:43:50 -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 , Kurt Lidl 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> In-Reply-To: <53821B1F.8000509@freebsd.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: freebsd-sysinstall@freebsd.org, "Michael W. Lucas" 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 16:43:53 -0000 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