From owner-freebsd-fs@FreeBSD.ORG Sat Feb 8 16:28:32 2014 Return-Path: Delivered-To: freebsd-fs@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 ACA4070E for ; Sat, 8 Feb 2014 16:28:32 +0000 (UTC) Received: from mail-oa0-x22b.google.com (mail-oa0-x22b.google.com [IPv6:2607:f8b0:4003:c02::22b]) (using TLSv1 with cipher ECDHE-RSA-RC4-SHA (128/128 bits)) (No client certificate requested) by mx1.freebsd.org (Postfix) with ESMTPS id 6C56F198F for ; Sat, 8 Feb 2014 16:28:32 +0000 (UTC) Received: by mail-oa0-f43.google.com with SMTP id h16so5714737oag.2 for ; Sat, 08 Feb 2014 08:28:31 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20120113; h=mime-version:in-reply-to:references:date:message-id:subject:from:to :cc:content-type; bh=phXN8e1ukbOB+HsCr1WpapIdOGmyp0cv08PAWyQy81o=; b=FOKaA7lpYxjUNMMzylSul9jx5arFr6jHxU4cYiuwsPRGfAhmf0inut2c7Ano7NxE7E 91ig294D/EOBzBAsi1C2c/9bk5c96Z5RGOyMpqV8SzduCVIWFLP6TdfCw/+VOl/CBlXW fzB3JQxjhjMZjL/QqpsbcDWwleaGfC9qNEYh6+H7d8vcS2UTkKiccVMnJ2OvSfWFCLtB Z79rS/TuWIrmtxf+M5bUBSSalaI5FDtX1AcSzmulBm0uNUM0k2H7pwzdHmvaAI+nPeAr Uuv59hFdJ7/nbH9pGTF5zLQWGsUgQoJNHQnvirveFjIPe32GuETxXpR7+rnezoNKH/L4 qy+Q== MIME-Version: 1.0 X-Received: by 10.60.67.105 with SMTP id m9mr971603oet.58.1391876911536; Sat, 08 Feb 2014 08:28:31 -0800 (PST) Received: by 10.76.180.164 with HTTP; Sat, 8 Feb 2014 08:28:31 -0800 (PST) Received: by 10.76.180.164 with HTTP; Sat, 8 Feb 2014 08:28:31 -0800 (PST) In-Reply-To: References: <1487AF77-7731-4AF8-8E44-FF814BB8A717@ebureau.com> <1391808195.4799.80708189.5CAD8A4E@webmail.messagingengine.com> <8B5D8D0C-ADDE-49B3-87A9-DE1105E32BF9@ebureau.com> <878utmxtum.wl%berend@pobox.com> Date: Sat, 8 Feb 2014 08:28:31 -0800 Message-ID: Subject: Re: Using the *real* sector/block size of a mass storage device for ZFS From: Freddie Cash To: Johan Hendriks Content-Type: text/plain; charset=UTF-8 X-Content-Filtered-By: Mailman/MimeDel 2.1.17 Cc: FreeBSD Filesystems X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.17 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sat, 08 Feb 2014 16:28:32 -0000 On Feb 8, 2014 2:03 AM, "Johan Hendriks" wrote: > > Op zaterdag 8 februari 2014 heeft Berend de Boer het > volgende geschreven: > > > >>>>> "Dustin" == Dustin Wenz > > > writes: > > > > Dustin> Am I correct in assuming that it is absolutely impossible > > Dustin> to convert an existing ashift:9 vdev to ashift:12? Some of > > Dustin> my pools are approaching 1PB in size; transferring the > > Dustin> data off and back again would be inconvenient. > > > > I thought you could do it one disk at a time (if you have a redundant > > pool). > > > > But maybe not. > > > > -- > > All the best, > > > > Berend de Boer > > > No that is not possible. > The ashift is set when the pool is created, hence the fact that you only > need the gnop method at pool creation time. If you add a vdev to the pool > you do not need the gnop method anymore because you can not change it. > You can align the disk so it has a 4 k alignement. But that is not the > ashift of the pool Correction: the ashift is set at the vdev level, when the vdev is created. You only need to use the gnop method on a single disk in a vdev as zfs uses the largest ashift of all drives in the vdev. And you need to do it anytime you add a new vdev to a pool. I believe there's a sysctl in FreeBSD 10 where you can set the minimum ashift level so you don't need to use the gnop method.