From owner-freebsd-stable@FreeBSD.ORG Sun Mar 22 09:07:50 2009 Return-Path: Delivered-To: freebsd-stable@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 9EF2D106566C for ; Sun, 22 Mar 2009 09:07:50 +0000 (UTC) (envelope-from uspoerlein@gmail.com) Received: from acme.spoerlein.net (cl-43.dus-01.de.sixxs.net [IPv6:2a01:198:200:2a::2]) by mx1.freebsd.org (Postfix) with ESMTP id 0FD3F8FC15 for ; Sun, 22 Mar 2009 09:07:49 +0000 (UTC) (envelope-from uspoerlein@gmail.com) Received: from roadrunner.spoerlein.net (e180181093.adsl.alicedsl.de [85.180.181.93]) by acme.spoerlein.net (8.14.3/8.14.3) with ESMTP id n2M97iIc050715 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK); Sun, 22 Mar 2009 10:07:46 +0100 (CET) (envelope-from uspoerlein@gmail.com) Received: from roadrunner.spoerlein.net (localhost [127.0.0.1]) by roadrunner.spoerlein.net (8.14.3/8.14.3) with ESMTP id n2M97fAi003351 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=NO); Sun, 22 Mar 2009 10:07:41 +0100 (CET) (envelope-from uspoerlein@gmail.com) Received: (from uqs@localhost) by roadrunner.spoerlein.net (8.14.3/8.14.3/Submit) id n2M97faE003350; Sun, 22 Mar 2009 10:07:41 +0100 (CET) (envelope-from uspoerlein@gmail.com) Date: Sun, 22 Mar 2009 10:07:40 +0100 From: Ulrich =?utf-8?B?U3DDtnJsZWlu?= To: Pete French , freebsd-stable@freebsd.org Message-ID: <20090322090740.GA1519@roadrunner.spoerlein.net> Mail-Followup-To: Pete French , freebsd-stable@freebsd.org References: <20090321184440.GA29399@lava.net> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20090321184440.GA29399@lava.net> User-Agent: Mutt/1.5.19 (2009-01-05) Cc: Subject: Re: gemor mirror and priority X-BeenThere: freebsd-stable@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 22 Mar 2009 09:07:50 -0000 On Sat, 21.03.2009 at 08:44:42 -1000, Clifton Royston wrote: > Even if you don't, I think it's quite useful to make the *default* > priority set when creating a mirror be some value which allows both > higher and lower values to be specified. I hadn't known about that > issue until I read the original thread here a while back.If the default > were set to some mid-range value, or even to 2, for example, then at > least creating a new mirror and adding drives without setting a > priority would continue to behave as usual, while it would be possible > to explicitly insert new components with a lower priority. (I see why > one wouldn't want to change the default interpretation of existing > priority values for POLA reasons.) > > There are lots of reasons one could want to control priorities of > mirrored drives in various ways. One is to use gmirror as a long-term > backup approach: mirror with three drives, periodically disconnecting > one from the mirror to swap it with a fresh drive from a pool of backup > drives. I haven't tried this, but it's been on my mind to mess around > with soon. I did this for 2-3 years and it has worked very well. Of course I took care of using the right priorities from the start. This setup has now been replaced by a ZFS mirror. The resilver time is just so much better :) > In this case, I would want the designated backup drive to always be > lowest-priority, to ensure the mirror never accidentally started > rebuilding from a newly reinserted backup. (This probably wouldn't > happen anyway, but it would be nice to be sure...) This will not happen. Besides, I would strongly encourage you to disable automatic rebuilding for this type of setup. Cheers, Ulrich Spörlein -- None are more hopelessly enslaved than those who falsely believe they are free -- Johann Wolfgang von Goethe