From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-oi0-f46.google.com ([209.85.218.46]:36457 "EHLO mail-oi0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753753AbcGDUnc convert rfc822-to-8bit (ORCPT ); Mon, 4 Jul 2016 16:43:32 -0400 Received: by mail-oi0-f46.google.com with SMTP id f189so206275231oig.3 for ; Mon, 04 Jul 2016 13:43:31 -0700 (PDT) MIME-Version: 1.0 In-Reply-To: References: <95f58623-95a4-b5d2-fa3a-bfb957840a31@gmail.com> From: Chris Murphy Date: Mon, 4 Jul 2016 14:43:30 -0600 Message-ID: Subject: Re: Unable to mount degraded RAID5 To: =?UTF-8?B?VG9tw6HFoSBIcmRpbmE=?= Cc: Chris Murphy , Btrfs BTRFS Content-Type: text/plain; charset=UTF-8 Sender: linux-btrfs-owner@vger.kernel.org List-ID: On Mon, Jul 4, 2016 at 1:11 PM, Tomáš Hrdina wrote: > Result from dmesg: > http://sebsauvage.net/paste/?4e8e95b5eafbf675#ybToBzZ/WAoRjjugeH6N2YXZKEBlswaNI/J41GBmFYU= [10849.041749] BTRFS info (device sda): allowing degraded mounts [10849.041754] BTRFS info (device sda): disk space caching is enabled [10849.041756] BTRFS: has skinny extents [10849.090553] BTRFS error (device sda): bad tree block start 10160120763642806272 12678831570944 [10849.090676] BTRFS error (device sda): bad tree block start 10160120763642806272 12678831570944 [10849.090700] BTRFS: failed to read chunk tree on sda [10849.100153] BTRFS: open_ctree failed Try 'mount -o ro,degraded,recovery > > sudo btrfs check /dev/sda > warning, device 3 is missing > checksum verify failed on 12678831570944 found 3DC57E3E wanted 771D2379 > checksum verify failed on 12678831570944 found 3DC57E3E wanted 771D2379 > bytenr mismatch, want=12678831570944, have=10160133442474442752 > Couldn't read chunk tree > Couldn't open file system Want and have are way far apart. If the mount command above still fails then I'd like to see: # btrfs-show-super -fa /dev/sda # btrfs-show-super -fa /dev/sdb Pretty much look for any discrepancies in generation, root and chunk_root addresses, both in the main part of the super as well as in the backups. # btrfs-find-root /dev/sda Maybe it's possible to use a different tree to get it mounted. I don't know what happened but merely a failing device should not either break checksums or lose the ability to mount the proper tree; but for sure one of the backups should work. Have you done a scrub on this file system and do you know if anything was fixed or if it always found no problem? -- Chris Murphy