From owner-freebsd-stable@freebsd.org Tue Nov 17 08:23:07 2015 Return-Path: Delivered-To: freebsd-stable@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 6876AA31DC0; Tue, 17 Nov 2015 08:23:07 +0000 (UTC) (envelope-from 000.fbsd@quip.cz) Received: from elsa.codelab.cz (elsa.codelab.cz [94.124.105.4]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by mx1.freebsd.org (Postfix) with ESMTPS id 247DA1A2D; Tue, 17 Nov 2015 08:23:06 +0000 (UTC) (envelope-from 000.fbsd@quip.cz) Received: from elsa.codelab.cz (localhost [127.0.0.1]) by elsa.codelab.cz (Postfix) with ESMTP id DBF7A28431; Tue, 17 Nov 2015 09:22:57 +0100 (CET) Received: from illbsd.quip.test (ip-86-49-16-209.net.upcbroadband.cz [86.49.16.209]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by elsa.codelab.cz (Postfix) with ESMTPSA id C13682842B; Tue, 17 Nov 2015 09:22:56 +0100 (CET) Message-ID: <564AE3E0.9060209@quip.cz> Date: Tue, 17 Nov 2015 09:22:56 +0100 From: Miroslav Lachman <000.fbsd@quip.cz> User-Agent: Mozilla/5.0 (X11; FreeBSD amd64; rv:35.0) Gecko/20100101 Firefox/35.0 SeaMonkey/2.32 MIME-Version: 1.0 To: "Patrick M. Hausen" , Freddie Cash CC: freebsd-scsi@freebsd.org, freebsd-stable Subject: Re: ZFS on labelled partitions References: <5644FF09.9090200@free.de> <56472686.5030301@free.de> <20151114143104.GA41119@in-addr.com> <7710CBCC-E68F-4454-9E29-E50ED1C6B511@sarenet.es> <20151116205734.GM48728@zxy.spb.ru> <878D84A9-4553-413B-ACA4-5ABF499F28C1@punkt.de> In-Reply-To: <878D84A9-4553-413B-ACA4-5ABF499F28C1@punkt.de> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.20 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 17 Nov 2015 08:23:07 -0000 Patrick M. Hausen wrote on 11/17/2015 09:08: > Hi, all, > >> Am 16.11.2015 um 22:19 schrieb Freddie Cash : >> >> ​You label the disks as they are added to the system the first time. That >> way, you always know where each disk is located, and you only deal with the >> labels. > > we do the same for obvious reasons. But I always wonder about the possible > downsides, because ZFS documentation explicitly states: > > ZFS operates on raw devices, so it is possible to create a storage pool comprised of logical > volumes, either software or hardware. This configuration is not recommended, as ZFS works > best when it uses raw physical devices. Using logical volumes might sacrifice performance, > reliability, or both, and should be avoided. > > (from http://docs.oracle.com/cd/E19253-01/819-5461/gbcik/index.html) > > Can anyone shed some lght on why not using raw devices might sacrifice > performance or reliability? Or is this just outdated folklore? It was on Solaris but not on FreeBSD. If you were using partitions on Solaris the drive cache was disabled (or something like that, I am not 100% sure) Miroslav Lachman