From owner-freebsd-fs@FreeBSD.ORG Sun Mar 28 07:06:40 2010 Return-Path: Delivered-To: freebsd-fs@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 521FF1065670 for ; Sun, 28 Mar 2010 07:06:40 +0000 (UTC) (envelope-from me@lexasoft.ru) Received: from relay.wahome.ru (relay.wahome.ru [95.211.21.141]) by mx1.freebsd.org (Postfix) with ESMTP id 17EF58FC12 for ; Sun, 28 Mar 2010 07:06:39 +0000 (UTC) Received: from mmx.lexasoft.ru (mmx.lexasoft.ru [92.241.160.6]) by relay.wahome.ru (Postfix) with ESMTP id BEE946B212E for ; Sun, 28 Mar 2010 11:03:47 +0400 (MSD) Received: from [192.168.40.138] (unknown [124.157.205.118]) by mmx.lexasoft.ru (Postfix) with ESMTPSA id 5F3CA28490; Sun, 28 Mar 2010 11:06:35 +0400 (MSD) From: Alexey Tarasov Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Date: Sun, 28 Mar 2010 11:06:29 +0400 Message-Id: To: freebsd-fs@freebsd.org Mime-Version: 1.0 (Apple Message framework v1077) X-Mailer: Apple Mail (2.1077) Cc: Subject: ZFS raidz and 4k sector disks X-BeenThere: freebsd-fs@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Filesystems List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 28 Mar 2010 07:06:40 -0000 Hello. I have reviewed a lot of discussion about new WD 4k sector disks = (...EARS). I have RAIDZ pool of such disks with very bad performance. Now my GPT = ZFS partitions don't start from value dividable by 4 (162). Some guys noticed that aligning ZFS partitions according to = recommendation wouldn't help at all because RAIDZ uses variable stripe = size. So where is the bottleneck of this configuration: 1) in ZFS which = doesn't know about 4k sectorsize? 2) maybe somewhere inside FreeBSD VFS = code or disk driver code? 3) somewhere else? If you doesn't want to use ZFS there are two ways to deal with this = problem: 1) Use GNOP with virtual 4k sectorsize. 2) Use UFS on properly aligned partition and some tuning. -- Alexey Tarasov (\__/)=20 (=3D'.'=3D)=20 E[: | | | | :]=D0=97=20 (")_(")