From owner-freebsd-stable@FreeBSD.ORG Wed Sep 10 06:51:08 2014 Return-Path: Delivered-To: freebsd-stable@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 2FF77D16 for ; Wed, 10 Sep 2014 06:51:08 +0000 (UTC) Received: from smtp2.wemm.org (smtp2.wemm.org [IPv6:2001:470:67:39d::78]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client CN "smtp2.wemm.org", Issuer "StartCom Class 1 Primary Intermediate Server CA" (not verified)) by mx1.freebsd.org (Postfix) with ESMTPS id 0F0E810E for ; Wed, 10 Sep 2014 06:51:07 +0000 (UTC) Received: from overcee.wemm.org (canning.wemm.org [192.203.228.65]) by smtp2.wemm.org (Postfix) with ESMTP id 09E16385; Tue, 9 Sep 2014 23:51:07 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=wemm.org; s=m20140428; t=1410331867; bh=d0hSeuFaIlqOihB5PD04ctY+QUKC+dT1w2yDXH7/vlM=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=q5GnnD4NJSEpTEp6ZHyqAkQI6E3Fkmi1ahWuXTTVBoglA8FD1VhdaIeXdZJvzAe3N wlTtv08puwVSLxzhm38mB3dVcQ9nor2vOAe2gJmqRqnlQOzeKyfF1+nMFwxzCE7r8W DKPE5UHJgNm0dwgrS9dpVwbrP2eArTBsUZ/AUXwA= From: Peter Wemm To: freebsd-stable@freebsd.org Subject: Re: getting to 4K disk blocks in ZFS Date: Tue, 09 Sep 2014 23:51:01 -0700 Message-ID: <6384455.xLarv7m8fO@overcee.wemm.org> User-Agent: KMail/4.12.5 (FreeBSD/11.0-CURRENT; KDE/4.12.5; amd64; ; ) In-Reply-To: <540FF3C4.6010305@ish.com.au> References: <540FF3C4.6010305@ish.com.au> MIME-Version: 1.0 Content-Type: multipart/signed; boundary="nextPart1622072.FDWEii6vFl"; micalg="pgp-sha1"; protocol="application/pgp-signature" Cc: Aristedes Maniatis X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.18-1 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Wed, 10 Sep 2014 06:51:08 -0000 --nextPart1622072.FDWEii6vFl Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="us-ascii" On Wednesday, September 10, 2014 04:46:28 PM Aristedes Maniatis wrote: > As we all know, it is important to ensure that modern disks are set u= p > properly with the correct block size. Everything is good if all the d= isks > and the pool are "ashift=3D9" (512 byte blocks). But as soon as one n= ew drive > requires 4k blocks, performance drops through the floor of the enture= pool. [..] > And secondly, is it also bad to have ashift 9 disks inside a ashift 1= 2 pool? > That is, do we need to replace all our disks in one go and forever ke= ep big > sticky labels on each disk so we never mix them? For what its worth, in the freebsd.org cluster we automatically align=20= everything to a minimum of 4k, no matter what the actual drive is. We set: sysctl vfs.zfs.min_auto_ashift=3D12 (this saves a lot of messing around with gnop etc) and ensure all the gpt slices are 4k or better aligned. =2D-=20 Peter Wemm - peter@wemm.org; peter@FreeBSD.org; peter@yahoo-inc.com; KI= 6FJV UTF-8: for when a ' or ... just won\342\200\231t do\342\200\246 --nextPart1622072.FDWEii6vFl Content-Type: application/pgp-signature; name="signature.asc" Content-Description: This is a digitally signed message part. Content-Transfer-Encoding: 7Bit -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQEcBAABAgAGBQJUD/TaAAoJEDXWlwnsgJ4EQQMIAKq8KMWaXMqm1Wwhc4rfCl7x FgSiNZpvHu6fIhbwhEQCdsDwoq2igztanzemMh50Kz5TV9FBLs99ol20q1FKiKxv 385emfODj5uODDCiQTBnwjtk6yP/z2aOs7YWutFBgaM2Ar22oDEONgquwof+8hSj 4lIO8eOjb0yovI4EtOC0h79aOSSGsptRjAQGUQO4NeolLIyY5ZmVV+/mlKMQGL3c KW5VNWxOOC9ZV9rtwtjLn2TeZfS5a6kaeYzr3fB6SGhDQStQrMyWLisp+g/Tqafa SUoIxFInZL8tZ/d+YlELsd/aRniHcfKsiGYDESrzeXT3Bgwv4vw75PTFd89t58A= =WOXD -----END PGP SIGNATURE----- --nextPart1622072.FDWEii6vFl--