From owner-freebsd-stable@FreeBSD.ORG Wed May 14 00:37:03 2008 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 AF8E31065670 for ; Wed, 14 May 2008 00:37:03 +0000 (UTC) (envelope-from mcdouga9@egr.msu.edu) Received: from mx.egr.msu.edu (surfnturf.egr.msu.edu [35.9.37.164]) by mx1.freebsd.org (Postfix) with ESMTP id 84B568FC0A for ; Wed, 14 May 2008 00:37:03 +0000 (UTC) (envelope-from mcdouga9@egr.msu.edu) Received: from localhost (localhost [127.0.0.1]) by mx.egr.msu.edu (Postfix) with ESMTP id 0B5F271F12D; Tue, 13 May 2008 20:37:03 -0400 (EDT) X-Virus-Scanned: amavisd-new at egr.msu.edu Received: from mx.egr.msu.edu ([127.0.0.1]) by localhost (surfnturf.egr.msu.edu [127.0.0.1]) (amavisd-new, port 10024) with ESMTP id Zht3A92NdNC3; Tue, 13 May 2008 20:37:02 -0400 (EDT) Received: from [35.9.40.72] (eb2314p12.egr.msu.edu [35.9.40.72]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) (Authenticated sender: mcdouga9) by mx.egr.msu.edu (Postfix) with ESMTPSA id C60BF71F121; Tue, 13 May 2008 20:37:02 -0400 (EDT) Message-ID: <482A342B.1020606@egr.msu.edu> Date: Tue, 13 May 2008 20:36:59 -0400 From: mcdouga9 User-Agent: Thunderbird 2.0.0.0 (Windows/20070326) MIME-Version: 1.0 To: hartzell@alerce.com References: <18473.48984.31132.91673@almost.alerce.com> <4829FBC8.5040101@egr.msu.edu> <18474.3218.145536.664367@almost.alerce.com> In-Reply-To: <18474.3218.145536.664367@almost.alerce.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Cc: freebsd-stable@freebsd.org Subject: Re: good/best practices for gmirror and gjournal on a pair of disks? 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: Wed, 14 May 2008 00:37:03 -0000 George Hartzell wrote: > Adam McDougall writes: > > George Hartzell wrote: > > >[...] > > > - I've read in the gjournal man page that when it is "... configured > > > on top of gmirror(8) or graid3(8) providers, it also keeps them in > > > a consistent state..." I've been trying to figure out if this > > > simply falls out of how gjournal works or if there's explicity > > > collusion with gmirror/graid3 but can't come up with a > > > satisfactory explanation. Can someone walk me through it? > > > > > > Since I'm only gjournal'ing a portion of the underlying gmirror > > > device I assume that I don't get this benefit? > > >[...] > > [...] > > I decided to journal /usr /var /tmp and leave / as a standard UFS > > partition because it is so small, fsck doesn't take long anyway and > > hopefully doesn't get written to enough to cause damage by an abrupt > > reboot. Because I'm not journaling the root partition, I chose to > > ignore the possibility of gjournal marking the mirror clean. Sudden > > reboots don't happen enough on servers for me to care. And all my > > servers got abruptly rebooted this sunday and they all came up fine :) > > [...] > > So you're confirming my belief that setting up gjournal on a > bsdlabel'ed partition of a gmirror does *not* provide the consistency > guarantee and that I should leave autosynchronization enabled. Right? > > g. > I forgot to address that. I think to gain that, you have to (re)label the mirror using -F (see man gmirror). I believe without using -F, the mirrors will still be synced (but probably don't need to). Otherwise, look for initial mail list announcements (freebsd-current?) of gjournal which may explain.