From owner-freebsd-stable@FreeBSD.ORG Tue May 13 21:48:14 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 912611065670 for ; Tue, 13 May 2008 21:48:14 +0000 (UTC) (envelope-from hartzell@alerce.com) Received: from merlin.alerce.com (merlin.alerce.com [64.62.142.94]) by mx1.freebsd.org (Postfix) with ESMTP id 78B848FC13 for ; Tue, 13 May 2008 21:48:14 +0000 (UTC) (envelope-from hartzell@alerce.com) Received: from merlin.alerce.com (localhost [127.0.0.1]) by merlin.alerce.com (Postfix) with ESMTP id 3957333C62; Tue, 13 May 2008 14:48:14 -0700 (PDT) Received: from postfix.alerce.com (w092.z064001164.sjc-ca.dsl.cnc.net [64.1.164.92]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (Client did not present a certificate) by merlin.alerce.com (Postfix) with ESMTP id 5411A33C5B; Tue, 13 May 2008 14:48:13 -0700 (PDT) Received: by postfix.alerce.com (Postfix, from userid 501) id 97C9042C6E6; Tue, 13 May 2008 14:48:02 -0700 (PDT) From: George Hartzell MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <18474.3218.145536.664367@almost.alerce.com> Date: Tue, 13 May 2008 14:48:02 -0700 To: Adam McDougall In-Reply-To: <4829FBC8.5040101@egr.msu.edu> References: <18473.48984.31132.91673@almost.alerce.com> <4829FBC8.5040101@egr.msu.edu> X-Mailer: VM 7.19 under Emacs 22.1.50.1 X-Virus-Scanned: ClamAV using ClamSMTP Cc: freebsd-stable@freebsd.org, hartzell@alerce.com 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 Reply-To: hartzell@alerce.com List-Id: Production branch of FreeBSD source code List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Tue, 13 May 2008 21:48:14 -0000 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.