From owner-freebsd-stable@FreeBSD.ORG  Wed Jul  2 14:15:08 2014
Return-Path: <owner-freebsd-stable@FreeBSD.ORG>
Delivered-To: freebsd-stable@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org
 [IPv6:2001:1900:2254:206a::19:1])
 (using TLSv1 with cipher ADH-AES256-SHA (256/256 bits))
 (No client certificate requested)
 by hub.freebsd.org (Postfix) with ESMTPS id A4A6D2A3
 for <freebsd-stable@freebsd.org>; Wed,  2 Jul 2014 14:15:08 +0000 (UTC)
Received: from wonkity.com (wonkity.com [67.158.26.137])
 (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits))
 (Client CN "wonkity.com", Issuer "wonkity.com" (not verified))
 by mx1.freebsd.org (Postfix) with ESMTPS id 409E929D9
 for <freebsd-stable@freebsd.org>; Wed,  2 Jul 2014 14:15:08 +0000 (UTC)
Received: from wonkity.com (localhost [127.0.0.1])
 by wonkity.com (8.14.9/8.14.9) with ESMTP id s62EEr6H089946
 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NO);
 Wed, 2 Jul 2014 08:14:53 -0600 (MDT)
 (envelope-from wblock@wonkity.com)
Received: from localhost (wblock@localhost)
 by wonkity.com (8.14.9/8.14.9/Submit) with ESMTP id s62EErwC089943;
 Wed, 2 Jul 2014 08:14:53 -0600 (MDT)
 (envelope-from wblock@wonkity.com)
Date: Wed, 2 Jul 2014 08:14:53 -0600 (MDT)
From: Warren Block <wblock@wonkity.com>
To: Dan Plassche <dplassche@gmail.com>
Subject: Re: Dump an Unmounted Journaled UFS Filesystem
In-Reply-To: <CAOD8Yqq5O1ZJ1RwGDTLnLtcvR0MhbLZEfWnOihaJL0xz875pOA@mail.gmail.com>
Message-ID: <alpine.BSF.2.11.1407020755250.89636@wonkity.com>
References: <CAOD8YqoB+ZpS9XBgFf2=WjWmsG5f9MsiwSis1cB3irKOOz=ZSw@mail.gmail.com>
 <CAOD8Yqq5O1ZJ1RwGDTLnLtcvR0MhbLZEfWnOihaJL0xz875pOA@mail.gmail.com>
User-Agent: Alpine 2.11 (BSF 23 2013-08-11)
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed
X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.4.3
 (wonkity.com [127.0.0.1]); Wed, 02 Jul 2014 08:14:53 -0600 (MDT)
Cc: freebsd-stable@freebsd.org
X-BeenThere: freebsd-stable@freebsd.org
X-Mailman-Version: 2.1.18
Precedence: list
List-Id: Production branch of FreeBSD source code <freebsd-stable.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/options/freebsd-stable>,
 <mailto:freebsd-stable-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-stable/>
List-Post: <mailto:freebsd-stable@freebsd.org>
List-Help: <mailto:freebsd-stable-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-stable>,
 <mailto:freebsd-stable-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Wed, 02 Jul 2014 14:15:08 -0000

On Tue, 1 Jul 2014, Dan Plassche wrote:

> I understand that using dump is not currently recommended on a mounted
> journaled UFS2 filesystem.  I prefer to boot from a separate FreeBSD drive
> for cold backups anyway, so I'm wondering if there are any issues with
> running dump on an unmounted journaled filesystem?  All the discussions
> I've seen seem to focus on disabling journaling completely, which I would
> like to avoid.

The snapshot code in sys/ufs/ffs/ffs_snapshot.c still prevents making 
snapshots on SUJ filesystems.

So pick the way that seems best: dump without a snapshot, use something 
other than dump like rsync, or turn off SUJ:
https://forums.freebsd.org/viewtopic.php?&t=41503

Some people have mentioned that they see crashes more frequently with 
SUJ enabled, so it might be both the cure and part of the problem.