From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from frost.carfax.org.uk ([85.119.82.111]:50326 "EHLO frost.carfax.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754384Ab3H2Tk5 (ORCPT ); Thu, 29 Aug 2013 15:40:57 -0400 Date: Thu, 29 Aug 2013 20:40:49 +0100 From: Hugo Mills To: Chris Murphy Cc: Zach Brown , Nick Lee , linux-btrfs Subject: Re: Question: How can I recover this partition? (unable to find logical $hugenum len 4096) Message-ID: <20130829194049.GR3115@carfax.org.uk> References: <6A12FF1B-5E1A-4F6F-92DA-41E52152E6F2@nickle.es> <20130826193110.GO3115@carfax.org.uk> <20130829173519.GN26818@lenny.home.zabbo.net> <528DF163-08F5-412D-8351-ACC853AC418D@colorremedies.com> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="GDLQamdgIxhPcIwq" In-Reply-To: <528DF163-08F5-412D-8351-ACC853AC418D@colorremedies.com> Sender: linux-btrfs-owner@vger.kernel.org List-ID: --GDLQamdgIxhPcIwq Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Thu, Aug 29, 2013 at 01:37:51PM -0600, Chris Murphy wrote: > > On Aug 29, 2013, at 11:35 AM, Zach Brown wrote: > > >> If those fail, then look in dmesg for errors relating to the log > >> tree -- if that's corrupt and can't be read (or causes a crash), use > >> btrfs-zero-log. > > > > In a bit of a tangent: > > > > btrfs-zero-log throws away data that fsync/sync could have previously > > claimed was stable on disk. > > > > Given how often this is thrown around as a solution to a broken > > partition, should the tool jump up and down and make it clear that it's > > about to roll the file system back? This seems like relevant > > information. > > > > Right now, as far as I can tell, it's completely undocumented and > > silent. > > Yes, I think it helps remove some burden on the list answering questions about a tool that doesn't have any documentation, to have a warning. > > How much longer will btrfs-zero-log be needed? If whatever it's doing isn't obviated by future improvements to btrfsck, and this sort of big hammer approach is still needed in some worse case scenarios, then it probably hurts no one to flag the user with essentially how you described it. I think documentation is a greater burden to create, and less likely to be consulted. > > "Proceeding will roll back the file system to a previous state, and may cause the loss of successfully written data. Proceed? (Y/N)" "... the loss of up to the last 30 seconds of successfully written data." Give the user enough information to make a sensible decision. Hugo. -- === Hugo Mills: hugo@... carfax.org.uk | darksatanic.net | lug.org.uk === PGP key: 65E74AC0 from wwwkeys.eu.pgp.net or http://www.carfax.org.uk --- emacs: Eighty Megabytes And Constantly Swapping. --- --GDLQamdgIxhPcIwq Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.14 (GNU/Linux) iQIVAwUBUh+jwVheFHXiqx3kAQK4tRAAsW2dcURtRUFRWKkq7J2Bkb1txj/ytzIF tSUtK+qVGuOR/3c2Tz5zUY8keUFiQ3l+OT1BF3bSex420Zx+xGyJH9LKY//tBPvr 71mCeK5D+0p0xbUhzjpbVw3kzT5Q/4jqvXGalm6VT28tprUM9NShwl6JxSEA6tUG 8qGr9DwViFOJNpiAt8Q7iV0IQGfG740XO6O2a6tIMJOmNji2I8lPgC8xVoTLaJ2s rznXXEXmsDGQVlfWLXdwgKPLy4aEZsa8hGXfxKM+S20wGlvaqCeGfTS+eri8ucdT wK2jYjEHZhZRdeYC768f/Z87w1p2MjCKlM2qtBGOLVwtixNbOfG0tcyhZz+AywXr C+tpZYhSzHCauYpWCVTc80SojkRsmde2kTgf5iRDa/fkKClK3kgwWQoJiepVbS3D Hx0n6Uwuu9BKEKmVGRdgicFWanNMr1DBh11Q9oJPFtIbevrZmioop2Zrn2bgMIRT w/mZiHDZqd7VbNNwUgvGi0BQ09H48DITN5JE6kkaOS4UaaCnmXzBcZP2+k6M8PgA Vnm8FkPkY+XUCyYV+EgUK88TUlTIyZWrGGLPf3me90fo/tvrnW5ZMkuE2G80Olke 5A3uLLDfHZA5KLoMPgLVyCUfloPlH+jNuddBGU/X8733N2ZAstr/z4Pvup5Dxvd5 mxtPNIoOK2s= =9ReB -----END PGP SIGNATURE----- --GDLQamdgIxhPcIwq--