From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from plane.gmane.org ([80.91.229.3]:47581 "EHLO plane.gmane.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750808AbbEDQzK (ORCPT ); Mon, 4 May 2015 12:55:10 -0400 Received: from list by plane.gmane.org with local (Exim 4.69) (envelope-from ) id 1YpJe4-0000zg-QB for linux-btrfs@vger.kernel.org; Mon, 04 May 2015 18:55:05 +0200 Received: from c-24-5-205-109.hsd1.ca.comcast.net ([24.5.205.109]) by main.gmane.org with esmtp (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Mon, 04 May 2015 18:55:04 +0200 Received: from obiwantje by c-24-5-205-109.hsd1.ca.comcast.net with local (Gmexim 0.1 (Debian)) id 1AlnuQ-0007hv-00 for ; Mon, 04 May 2015 18:55:04 +0200 To: linux-btrfs@vger.kernel.org From: TheJay Subject: [REQ] Help to gain access to btrfsraid6 pool that won't mount Date: Mon, 4 May 2015 15:44:35 +0000 (UTC) Message-ID: Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Sender: linux-btrfs-owner@vger.kernel.org List-ID: $ uname -a Linux thejay-srv03 4.0.0-040000-generic #201504121935 SMP Sun Apr 12 23:36:33 UTC 2015 x86_64 x86_64 x86_64 GNU/Linux $ btrfs --version btrfs-progs v3.19.1 $ sudo btrfs fi show Label: 'roms03' uuid: b0025417-4045-4c63-a432-0625b7cc41ea Total devices 4 FS bytes used 2.67TiB devid 1 size 1.36TiB used 1.36TiB path /dev/sdz devid 3 size 1.36TiB used 1.36TiB path /dev/sdaa devid 4 size 1.36TiB used 1.36TiB path /dev/sdab *** Some devices missing This pool is a btrfsraid6 pool when trying to mount I get: $ sudo mount -t btrfs -o recovery,ro /dev/sdaa /mnt/roms03 mount: wrong fs type, bad option, bad superblock on /dev/sdaa, missing codepage or helper program, or other error In some cases useful info is found in syslog - try dmesg | tail or so $ dmesg -T|tail [Mon May 4 08:35:08 2015] BTRFS info (device sdz): enabling auto recovery [Mon May 4 08:35:08 2015] BTRFS info (device sdz): disk space caching is enabled [Mon May 4 08:35:08 2015] BTRFS: has skinny extents [Mon May 4 08:35:08 2015] BTRFS: failed to read chunk tree on sdz [Mon May 4 08:35:08 2015] BTRFS: open_ctree failed What could I try to see if I can mount this pool and gain access to the data? While I have a backup of the data, next time I may not, and I am trying to learn how to go about.