From owner-freebsd-questions@FreeBSD.ORG Mon Feb 22 15:10:14 2010 Return-Path: Delivered-To: questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id EBD45106566B for ; Mon, 22 Feb 2010 15:10:14 +0000 (UTC) (envelope-from m.seaman@infracaninophile.co.uk) Received: from smtp.infracaninophile.co.uk (gate6.infracaninophile.co.uk [IPv6:2001:8b0:151:1::1]) by mx1.freebsd.org (Postfix) with ESMTP id 5B2248FC15 for ; Mon, 22 Feb 2010 15:10:14 +0000 (UTC) Received: from seedling.black-earth.co.uk (seedling.black-earth.co.uk [81.187.76.163]) (authenticated bits=0) by smtp.infracaninophile.co.uk (8.14.4/8.14.4) with ESMTP id o1MFA1NB021647 (version=TLSv1/SSLv3 cipher=DHE-RSA-CAMELLIA256-SHA bits=256 verify=NO); Mon, 22 Feb 2010 15:10:02 GMT (envelope-from m.seaman@infracaninophile.co.uk) Message-ID: <4B829E49.3050202@infracaninophile.co.uk> Date: Mon, 22 Feb 2010 15:10:01 +0000 From: Matthew Seaman Organization: Infracaninophile User-Agent: Mozilla/5.0 (Macintosh; U; Intel Mac OS X 10.6; en-GB; rv:1.9.1.7) Gecko/20100111 Thunderbird/3.0.1 MIME-Version: 1.0 To: Jerry McAllister References: <4B80ABBA.9000707@comclark.com> <20100221110358.9ec8b286.freebsd@edvax.de> <20100222030127.GA41439@gizmo.acns.msu.edu> <4B8206AE.8080105@comclark.com> <20100222143028.GA43687@gizmo.acns.msu.edu> In-Reply-To: <20100222143028.GA43687@gizmo.acns.msu.edu> X-Enigmail-Version: 1.0.1 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Virus-Scanned: clamav-milter 0.95.3 at happy-idiot-talk.infracaninophile.co.uk X-Virus-Status: Clean X-Spam-Status: No, score=-1.1 required=5.0 tests=BAYES_00,DKIM_ADSP_ALL, SPF_FAIL autolearn=no version=3.3.0 X-Spam-Checker-Version: SpamAssassin 3.3.0 (2010-01-18) on happy-idiot-talk.infracaninophile.co.uk Cc: Aiza , freebsd-questions Subject: Re: Dump questions 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: Mon, 22 Feb 2010 15:10:15 -0000 -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1 On 22/02/2010 14:30, Jerry McAllister wrote: > No. In multi-user, files are still changing. The snapshot could > possibly be made between parts of a change - between different writes > to the file, so there could be some inconsistency. In practice this > is not a big problem, but, single user with filesystems unmounted is > still the most absolute way of making sure a filesystem is quiescent > during a dump. Umm.... you don't *need* to go to single user to ensure a consistent filesystem dump: unmounting the partition is sufficient, or remounting it read-only. It's just that shutting the system down and rebooting to single user mode can save you a deal of faffing about trying to kill off any processes still using the filesystem, which would otherwise block your ability to unmount it. Note too, it's *reboot* into single user ('shutdown -r now', then press 4 at the boot menu) not *drop* into single user ('shutdown now') which doesn't unmount filesystems for you, although it should kill almost all processes. Single user has it's own disadvantages: generally there's no network configured, and with the root partition mounted read-only, you can't update /etc/dumpdates. Whenever you boot into single user, remember to run 'fsck -p' to ensure filesystem integrity. I'm not sure what happens if you attempt to dump'n'restore a dirty filesystem, but it's certainly going to have unintended consequences if the filesystem is actually damaged rather than just dirty. Cheers, Matthew - -- Dr Matthew J Seaman MA, D.Phil. 7 Priory Courtyard Flat 3 PGP: http://www.infracaninophile.co.uk/pgpkey Ramsgate Kent, CT11 9PW -----BEGIN PGP SIGNATURE----- Version: GnuPG/MacGPG2 v2.0.14 (Darwin) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iEYEARECAAYFAkuCnkkACgkQ8Mjk52CukIyR+gCfX9rep9S9DQcIcRDqSoAptQX9 gMkAoIV/zhe4kRRlRN8fjn5+W7CS1csM =6J2U -----END PGP SIGNATURE-----