From owner-freebsd-questions@freebsd.org Sun Sep 13 21:43:04 2015 Return-Path: Delivered-To: freebsd-questions@mailman.ysv.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:1900:2254:206a::19:1]) by mailman.ysv.freebsd.org (Postfix) with ESMTP id A971CA049A7 for ; Sun, 13 Sep 2015 21:43:04 +0000 (UTC) (envelope-from wam@hiwaay.net) Received: from fly.hiwaay.net (fly.hiwaay.net [216.180.54.1]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 79A261C88 for ; Sun, 13 Sep 2015 21:43:03 +0000 (UTC) (envelope-from wam@hiwaay.net) Received: from kabini1.local (dynamic-216-186-213-32.knology.net [216.186.213.32] (may be forged)) (authenticated bits=0) by fly.hiwaay.net (8.13.8/8.13.8/fly) with ESMTP id t8DLguex032204 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES128-SHA bits=128 verify=NO) for ; Sun, 13 Sep 2015 16:42:57 -0500 Subject: Re: followup storage question To: freebsd-questions@freebsd.org References: <55F2D086.6060509@hiwaay.net> <55F2F2CF.3080004@physics.umn.edu> From: "William A. Mahaffey III" Message-ID: <55F5EDDF.8040108@hiwaay.net> Date: Sun, 13 Sep 2015 16:48:25 -0453.75 User-Agent: Mozilla/5.0 (X11; FreeBSD amd64; rv:38.0) Gecko/20100101 Thunderbird/38.2.0 MIME-Version: 1.0 In-Reply-To: <55F2F2CF.3080004@physics.umn.edu> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 13 Sep 2015 21:43:04 -0000 On 09/11/15 10:33, Graham Allan wrote: > On 9/11/2015 7:59 AM, William A. Mahaffey III wrote: >> >> >> The Wiki page https://wiki.freebsd.org/RootOnZFS/GPTZFSBoot/9.0-RELEASE >> illustrates using gnop to enforce 4K alignment of gpt partitions for >> subsequent use by ZFS. However the gpart commands also use the '-a 4k' >> arguments, aligning partitions on 4k boundaries as I understand things. >> Is the gnop command also necessary ? TIA & have a nice weekend. > > My experience is I only ever install on smaller devices so never > really worry about 4k alignment at that time, only for making large > storage pools later. With that mind mind here is my "easy" answer for > 9.3 and 10.x. The installer "auto ZFS" has a 4k alignment option which > I would assume works as advertised (having said that it would be > simple to do a basic install and then examine that to confirm). For > making subsequent pools, I simply set vfs.zfs.min_auto_ashift=12 is > /etc/sysctl.conf, after which you will get 4k block alignment without > messing with gnop. On 9.1 you had to do the gnop tricks but 9.3 > supports the auto_ashift sysctl. > > On 9.3+, "zpool status" also *tells you* if you got the block > alignment wrong, which is a big help over 9.1 where it could lurk > undetected! > > G. *Eeeeeeeeek* !!!!! [root@kabini1, /etc, 4:47:06pm] 332 % sysctl -A | grep ashift [root@kabini1, /etc, 4:47:10pm] 333 % uname -a FreeBSD kabini1.local 9.3-RELEASE-p24 FreeBSD 9.3-RELEASE-p24 #0: Sat Aug 22 01:54:44 UTC 2015 root@amd64-builder.daemonology.net:/usr/obj/usr/src/sys/GENERIC amd64 [root@kabini1, /etc, 4:47:15pm] 334 % I don't see that sysctl setting, am I missing something (No ZFS installed on this box, BTW) ? Thanks & TIA & have a nice weekend. -- William A. Mahaffey III ---------------------------------------------------------------------- "The M1 Garand is without doubt the finest implement of war ever devised by man." -- Gen. George S. Patton Jr.