From owner-freebsd-questions@FreeBSD.ORG Fri Dec 11 19:58:20 2009 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 1B483106568B for ; Fri, 11 Dec 2009 19:58:20 +0000 (UTC) (envelope-from freebsd-questions@m.gmane.org) Received: from lo.gmane.org (lo.gmane.org [80.91.229.12]) by mx1.freebsd.org (Postfix) with ESMTP id CB89F8FC13 for ; Fri, 11 Dec 2009 19:58:19 +0000 (UTC) Received: from list by lo.gmane.org with local (Exim 4.50) id 1NJBd3-0005yV-6c for freebsd-questions@freebsd.org; Fri, 11 Dec 2009 20:58:17 +0100 Received: from pool-68-239-72-201.res.east.verizon.net ([68.239.72.201]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Fri, 11 Dec 2009 20:58:17 +0100 Received: from nightrecon by pool-68-239-72-201.res.east.verizon.net with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Fri, 11 Dec 2009 20:58:17 +0100 X-Injected-Via-Gmane: http://gmane.org/ To: freebsd-questions@freebsd.org From: Michael Powell Followup-To: gmane.os.freebsd.questions Date: Fri, 11 Dec 2009 14:57:49 -0500 Lines: 39 Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain; charset="ISO-8859-1" Content-Transfer-Encoding: 7Bit X-Complaints-To: usenet@ger.gmane.org X-Gmane-NNTP-Posting-Host: pool-68-239-72-201.res.east.verizon.net User-Agent: KNode/4.3.4 Sender: news Subject: Re: use DD mode or not? and how to set up? X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 11 Dec 2009 19:58:20 -0000 Tom Worster wrote: > options for setting up gmirror include DD or standard mode. i don't know > about others. > > i'm about to install 8.0-RELEASE on a system with two 750g sata disks that > i want to run as a mirrored pair. > > what are the pros/cons of the different options? > > and what about the installation process? set up the mirror before > installing from the CD or do it like the handbook says? > I believe DD mode is going away. Probably has something to do with adding features to loader for GPT support. A GPT places what's called a "protective" MBR in the place where the old DOS style MBR would normally occupy. I would avoid DD. Last question is easy if dealing with a true hardware RAID card, as you will create the array in the card's BIOS and FreeBSD will just see that as ar0 and install to that. As far as a perfect answer I'm not certain. There is one little tidbit that may assist though. The metadata gets stored in the last sector at the end of an empty disk. As long as there is free space at the end of the drive(s) it won't matter which way you do it. The Handbook is essentially reconfiguring an already virgin install existing on the first drive. When rebooted into this changed configuration, the second drive is then added to the mirror and replication will take place. The less amount of data present will speed this replication and get you to mirrored status quicker. I've done this a couple of times and it was pretty straightforward. -Mike