From owner-freebsd-fs@FreeBSD.ORG Wed Jan 17 22:18:41 2007 Return-Path: X-Original-To: fs@freebsd.org Delivered-To: freebsd-fs@FreeBSD.ORG Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52]) by hub.freebsd.org (Postfix) with ESMTP id 7C4B516A492; Wed, 17 Jan 2007 22:18:41 +0000 (UTC) (envelope-from scottl@samsco.org) Received: from pooker.samsco.org (pooker.samsco.org [168.103.85.57]) by mx1.freebsd.org (Postfix) with ESMTP id 3AC3A13C44B; Wed, 17 Jan 2007 22:18:40 +0000 (UTC) (envelope-from scottl@samsco.org) Received: from phobos.samsco.home (phobos.samsco.home [192.168.254.11]) (authenticated bits=0) by pooker.samsco.org (8.13.4/8.13.4) with ESMTP id l0HMIY8Z076188; Wed, 17 Jan 2007 15:18:40 -0700 (MST) (envelope-from scottl@samsco.org) Message-ID: <45AEA0B5.8060903@samsco.org> Date: Wed, 17 Jan 2007 15:18:29 -0700 From: Scott Long User-Agent: Mozilla/5.0 (Macintosh; U; Intel Mac OS X; en-US; rv:1.8.1.2pre) Gecko/20070111 SeaMonkey/1.1 MIME-Version: 1.0 To: Andrew Pantyukhin References: <20070117103935.GC4018@genius.tao.org.uk> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-Greylist: Sender succeeded SMTP AUTH authentication, not delayed by milter-greylist-2.0.2 (pooker.samsco.org [168.103.85.57]); Wed, 17 Jan 2007 15:18:40 -0700 (MST) X-Spam-Status: No, score=-1.4 required=3.8 tests=ALL_TRUSTED autolearn=failed version=3.1.1 X-Spam-Checker-Version: SpamAssassin 3.1.1 (2006-03-10) on pooker.samsco.org Cc: Josef Karthauser , stable@freebsd.org, fs@freebsd.org Subject: Re: gmirror disks vs partitions 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: Wed, 17 Jan 2007 22:18:41 -0000 Andrew Pantyukhin wrote: > On 1/17/07, Josef Karthauser wrote: >> A poll for opinions if I may? >> >> I've got a few gmirrors running on various machines, all of which >> pair up two drives at the physical level (i.e. mirror /dev/ad0s1 >> with /dev/ad1s1). Of course there are other ways of doing it to, >> like mirroring at the partition level, ie pairing /dev/ad0s1a with >> /dev/ad1s1a, /dev/ad0s1e with /dev/ad0s1e, etc. >> >> Apart from potentially avoiding a whole disk from being copied >> during a resync after a crash, are there any other advantages to >> using partition level mirroring instead of drive level mirroring? > > I can imagine people using partition-level raid to > implement a popular configuration: > > You divide a couple of identical drives proportionally > in two partitions each, place a couple of the first > partitions into gmirror and a couple of the second > ones into gstripe. This way you get both reliable and > fast storage with just two drives. Some strings are > attached. The head movement that this causes makes it a poor performer. It is an option, but not a terribly popular one. Scott