Date: Tue, 12 Aug 2014 22:40:56 +0200 From: Roland Smith <rsmith@xs4all.nl> To: Andrew Hamilton-Wright <AHamiltonWright@MtA.ca> Cc: freebsd-questions@freebsd.org Subject: Re: Problems with dump and restore Message-ID: <20140812204056.GA7591@slackbox.erewhon.home> In-Reply-To: <alpine.BSF.2.11.1408121708140.1074@qemg.org> References: <alpine.BSF.2.11.1408121255230.1074@qemg.org> <20140812193419.GB7166@slackbox.erewhon.home> <alpine.BSF.2.11.1408121641480.1074@qemg.org> <alpine.BSF.2.11.1408121708140.1074@qemg.org>
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--azLHFNyN32YCQGCU Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Tue, Aug 12, 2014 at 05:14:56PM -0300, Andrew Hamilton-Wright wrote: >=20 > Sorry, a bit of a follow up after some reading, as the soft-update > bit was itching in my memory... >=20 >=20 > On Tue, 12 Aug 2014, Roland Smith wrote: >=20 > > In 2011, a problem was found with snapshots in combination with soft > > updates *and* journaling (SU+J) hanging the machine. At that time the > > recommendation was to switch off journaling. > > According to https://wiki.freebsd.org/NewFAQs: > > > > If you want to use snapshot (dump -L) then disable the soft updates > > journal for that filesystem. >=20 > I have just realize that the soft update journal (newfs option -j enable) > is actually not in play here, however "soft updates" (option -U) is. My > understanding of the referenced bug: > https://bugs.freebsd.org/bugzilla/show_bug.cgi?id=3D160662 > is that it is specifically referred to _journaled_ soft updates as being > a danger, but soft updates using -U are not referred to by this bug. >=20 > Is that your understanding as well? Yes. If you look at the mailing lists traffic around that time you'll see t= hat it was the *combination* of SU+J that had problems. > I believe that when I set up the filesystems for this machine in the first > place, I specifically ensured that "-j disable" was chosen, for exactly > this reason -- however my logbook does not contain enough detail for > me to be sure. Run `mount` and you'll see which options are set on your mounted filesystem= s; /dev/ada0p2 on / (ufs, local, noatime, journaled soft-updates) > To be clear then, do I understand that your filesystem options include > neither "-j enable" nor "-U"? No, I use SU+J. But I do dumps from single user mode on unmounted or read-o= nly filesystems so snapshots aren't used. And every month or so I run a *full* fsck before making the dumps. These measures might be considered an overabundance of caution on my part. But I've actually lost a couple harddisks due to hardware failure over the years. And since it's little effort I'd rather be safe than sorry. Roland --=20 R.F.Smith http://rsmith.home.xs4all.nl/ [plain text _non-HTML_ PGP/GnuPG encrypted/signed email much appreciated] pgp: 5753 3324 1661 B0FE 8D93 FCED 40F6 D5DC A38A 33E0 (keyID: A38A33E0) --azLHFNyN32YCQGCU Content-Type: application/pgp-signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 iQIcBAEBAgAGBQJT6nvYAAoJEED21dyjijPgKPUQALxDd7OccT6ZvWT2wOqTCxWS GCIZLDpln10Ga75XTewSOlIvH5/elnXhI7EJdBdDxh9Q4e7PIDbuTlG5oG5Xvldx FumhO1Gj5s7QCdO/Oe5Yq0uYDj4MnkV8XGrIsoJHVF+z61htybpQUbh96DYeglPC 7w1js9tGRprWpfVATHs+oU4YJtkEpAl4lUbDseQ8f4qm6dJLjJUvkZCY1Kwd6TxL lTeh4ByHtM3hxiOfmHy9fHpxPyXFHupC7k4r1eeaaF+3T4J1PrxKZ3NcMWuRavgt lqLO1d1md/fSr4U5mGvos1BWGQt2xhROR4oG6gEQ7mucbTs3nW4ZxOdINnKRmQP/ YRJF8FluruWEeluFxiizgYoSXetK/EFf00N6cw7aonCwhZrr3cPgt3WwglUAYELN P/DApSA0Pe0mR1bB3QzIc5IJYuWM4eKbi/9rE+GcHUpz7zYZ1NrT90MsGvWT8UPj ZpfLkJJiOcuR1QPx5K0L0NC0PDXryge/eyaIgnI1ozRPlqLA1YfRlMG1gRC4LcgE hO2ozwgE6QQywmxfi1ChtdciC+oS+jQ2xwXy+0diTMy0I9ooV9ZbgjNyTwi2cGtV KyrLDjTb+bOLAt09wadxM6+uj7IvIVGZjaW88GPyvWpgBiUECCPwcCf/JTrtKcxj jsxQVn8Dz05OvI30r3xY =rrdr -----END PGP SIGNATURE----- --azLHFNyN32YCQGCU--
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