From owner-freebsd-questions@FreeBSD.ORG Tue Feb 23 18:14:59 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 CF208106566B for ; Tue, 23 Feb 2010 18:14:59 +0000 (UTC) (envelope-from jerrymc@gizmo.acns.msu.edu) Received: from gizmo.acns.msu.edu (gizmo.acns.msu.edu [35.8.1.43]) by mx1.freebsd.org (Postfix) with ESMTP id 8E46F8FC12 for ; Tue, 23 Feb 2010 18:14:59 +0000 (UTC) Received: from gizmo.acns.msu.edu (localhost [127.0.0.1]) by gizmo.acns.msu.edu (8.13.6/8.13.6) with ESMTP id o1NICFRX049718; Tue, 23 Feb 2010 13:12:15 -0500 (EST) (envelope-from jerrymc@gizmo.acns.msu.edu) Received: (from jerrymc@localhost) by gizmo.acns.msu.edu (8.13.6/8.13.6/Submit) id o1NIC3nu049717; Tue, 23 Feb 2010 13:12:03 -0500 (EST) (envelope-from jerrymc) Date: Tue, 23 Feb 2010 13:12:03 -0500 From: Jerry McAllister To: Matthew Seaman Message-ID: <20100223181203.GB49549@gizmo.acns.msu.edu> 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> <4B829E49.3050202@infracaninophile.co.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4B829E49.3050202@infracaninophile.co.uk> User-Agent: Mutt/1.4.2.2i Cc: Jerry McAllister , 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: Tue, 23 Feb 2010 18:15:00 -0000 On Mon, Feb 22, 2010 at 03:10:01PM +0000, Matthew Seaman wrote: > -----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. True. But, the problem with that, as you follow with is that it can produce a lot of fudd from parts of the running system that expect to find that file system mountable and writable. Plus some filesystems such as maybe /usr, etc may be needed for the multi-user system to operate at all. So, you either don't dump them or go to single user just for them or use -L and not worry about it, or whatever. ////jerry > 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----- > _______________________________________________ > freebsd-questions@freebsd.org mailing list > http://lists.freebsd.org/mailman/listinfo/freebsd-questions > To unsubscribe, send any mail to "freebsd-questions-unsubscribe@freebsd.org"