From owner-freebsd-questions@FreeBSD.ORG Thu Aug 31 17:17:51 2006 Return-Path: X-Original-To: freebsd-questions@freebsd.org Delivered-To: freebsd-questions@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id BF97C16A4DA for ; Thu, 31 Aug 2006 17:17:51 +0000 (UTC) (envelope-from david.robillard@gmail.com) Received: from ug-out-1314.google.com (ug-out-1314.google.com [66.249.92.170]) by mx1.FreeBSD.org (Postfix) with ESMTP id 23C7443D45 for ; Thu, 31 Aug 2006 17:17:50 +0000 (GMT) (envelope-from david.robillard@gmail.com) Received: by ug-out-1314.google.com with SMTP id m2so667277uge for ; Thu, 31 Aug 2006 10:17:50 -0700 (PDT) DomainKey-Signature: a=rsa-sha1; q=dns; c=nofws; s=beta; d=gmail.com; h=received:message-id:date:from:to:subject:cc:mime-version:content-type:content-transfer-encoding:content-disposition; b=Hila+VnjLxqTsQqRP+Ng0EQX0Nx9sZfaGJgmPFV3FZDBjDJEFbAs9Cq/P8ZvEhIT2HVPN0RsgiLHAE96WrKlxAMIA/OARk+xGDqjwXFysXpN2KMZGZWBAbymXfxqOLFjakNTrMVOchdHUB+5XEroyTyMbiWSnHmllHhaxsxW3Xg= Received: by 10.67.89.5 with SMTP id r5mr668098ugl; Thu, 31 Aug 2006 10:17:50 -0700 (PDT) Received: by 10.67.106.17 with HTTP; Thu, 31 Aug 2006 10:17:50 -0700 (PDT) Message-ID: <226ae0c60608311017j1a4bea9cg6dbaa12414d74716@mail.gmail.com> Date: Thu, 31 Aug 2006 13:17:50 -0400 From: "David Robillard" To: "Jonathan McKeown" MIME-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Content-Disposition: inline Cc: FreeBSD Questions Mailing List Subject: Re: Mirroring: gvinum or gmirror? 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: Thu, 31 Aug 2006 17:17:51 -0000 > I'm setting up a remote server with two identical hard drives, running > FreeBSD-6.1. I want to set the drives up as a mirror for data redundancy. I > also want to be able to break the mirror when I need to update the OS or > installed software, so that if anything goes wrong with the update on one > drive I can boot back to the other one, or if all is well, re-establish the > mirror and synchronise to the updated system. I have serial console access > including BIOS console redirection. > > Based on web and Usenet/mailing list searches, gmirror looks more > straightforward for this simple case, gvinum more flexible but poorly > documented, and the most recent comments I can find (still all 6+ months ago) > seem to suggest that gvinum hasn't completely stabilised for production yet. > > Is this a fair assessment? Are there any factors I've missed? Which solution > is likely to suit the situation better? > > Jonathan Hello Jonathan, I run gmirror on all machines which don't have a hardware RAID controller. I've had drive failures in the past and gmirror handled it very well. It's now a lot better under 6.1 then 5.x (mostly concerning the kernel dump area and the swapoff option in rc.conf(5)). Take a look at Ralf S. Engelschall's documentation on the subject: http://people.freebsd.org/~rse/mirror/ Bonus Tip of the day! If you ever have two disk drives which are not identical, such as these: ad0: 4112MB at ata0-master UDMA33 ad3: 4028MB at ata1-slave UDMA33 Then make sure you install FreeBSD on the bigger one (i.e. here that would be ad0) then setup gmirror. If you do the oposite, you will have a "Consumers too small" error when you try to bring the mirror together. Finally, keep in mind that gmirror is only good for RAID 1. If you need more powerfull volume management tools such as Veritas Volume Manager or Sun DiskSuite, then you need gvinum. Regards, David -- David Robillard UNIX systems administrator & Oracle DBA CISSP, RHCE & Sun Certified Security Administrator Montreal: +1 514 966 0122