From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from frost.carfax.org.uk ([85.119.82.111]:59656 "EHLO frost.carfax.org.uk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753178AbbFQKLW (ORCPT ); Wed, 17 Jun 2015 06:11:22 -0400 Date: Wed, 17 Jun 2015 10:11:21 +0000 From: Hugo Mills To: Marc MERLIN Cc: linux-btrfs Subject: Re: BTRFS: read error corrected: ino 1 off 226840576 (dev /dev/mapper/dshelf1 sector 459432) Message-ID: <20150617101121.GQ9850@carfax.org.uk> References: <20150617071654.GI16468@merlins.org> MIME-Version: 1.0 Content-Type: multipart/signed; micalg=pgp-sha1; protocol="application/pgp-signature"; boundary="v4cNTr+tRGSs1txX" In-Reply-To: <20150617071654.GI16468@merlins.org> Sender: linux-btrfs-owner@vger.kernel.org List-ID: --v4cNTr+tRGSs1txX Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Wed, Jun 17, 2015 at 12:16:54AM -0700, Marc MERLIN wrote: > I had a few power offs due to a faulty power supply, and my mdadm raid5 > got into fail mode after 2 drives got kicked out since their sequence > numbers didn't match due to the abrupt power offs. > > I brought the swraid5 back up by force assembling it with 4 drives (one > was really only a few sequence numbers behind), and it's doing a full > parity rebuild on the 5th drive that was farther behind. > > So I can understand how I may have had a few blocks that are in a bad > state. > I'm getting a few (not many) of those messages in syslog. > BTRFS: read error corrected: ino 1 off 226840576 (dev /dev/mapper/dshelf1 sector 459432) > > Filesystem looks like this: > Label: 'btrfs_pool1' uuid: 6358304a-2234-4243-b02d-4944c9af47d7 > Total devices 1 FS bytes used 8.29TiB > devid 1 size 14.55TiB used 8.32TiB path /dev/mapper/dshelf1 > > gargamel:~# btrfs fi df /mnt/btrfs_pool1 > Data, single: total=8.29TiB, used=8.28TiB > System, DUP: total=8.00MiB, used=920.00KiB > System, single: total=4.00MiB, used=0.00B > Metadata, DUP: total=14.00GiB, used=10.58GiB > Metadata, single: total=8.00MiB, used=0.00B > GlobalReserve, single: total=512.00MiB, used=0.00B > > Kernel 3.19.8. > > Just to make sure I understand, do those messages in syslog mean that my > metadata got corrupted a bit, but because I have 2 copies, btrfs can fix > the bad copy by using the good one? > > Also, if my actual data got corrupted, am I correct that btrfs will > detect the checksum failure and give me a different error message of a > read error that cannot be corrected? Yes, that's my reading of the situation. Note that the 3.19 kernel is the earliest I would expect this to be able to happen, as it's the first kernel that actually had the full set of parity RAID repair code in it. > I'll do a scrub later, for now I have to wait 20 hours for the raid rebuild > first. You'll probably find that the rebuild is equivalent to a scrub anyway. Hugo. -- Hugo Mills | If you're not part of the solution, you're part of hugo@... carfax.org.uk | the precipiate. http://carfax.org.uk/ | PGP: E2AB1DE4 | --v4cNTr+tRGSs1txX Content-Type: application/pgp-signature; name="signature.asc" Content-Description: Digital signature -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) iQIcBAEBAgAGBQJVgUfJAAoJEFheFHXiqx3knsMQAIpCGdJI+j2ozKm49yZ6x6RK 4BmEDnY+3dGKjq8eG/Z5L3Vvw+uriiUDeUCNPglaT/4utAVtHAxKgE3sHVvpwBRz PzQDhRwKmfrIwYxCB7CPztYgSyi8gDsp+vTws8YVESSHaZGoXCzDRVgOYxBlF4tU XSAdNY7DOxudpm9Zl0XrgkRLJ8ZGGqTmfI8mjAqVLUrGljPzzwp1qVaTivhjDxxU hdOP0WyYq8MQ3vU/NJqyUFxgImQJ1KxpeAxmaXaUPjl3E9r2ZE5k22nFZdh7WaMa v/hEs3wgWMqTe9Y3y/BOnMHdhpAHF8jLNegy/DKj3eT7kinU5pF+IsqPkUTkYnaF rIzpOBb8nEwlAoloJU//h7KGZU5unZ0E+BxbT70cT5renbXIf2z1fxmCd3a/63BZ DpsZwae6JMk+ISym6pny+KuVjVh54yJFl9myT+hcAesf/mLM6G3n37TMYU72r139 XaOJ6LAjf1mrCGiWB445r9jI0Z9CnSi90gpE434WMrUrVJHPo6diwSfPJwfkc1jZ CmTgB0BB9J1RQwOvblpxtGJ3NaAGTPTtI0j2YrVQe7hKM6pvL5gFHX9qBOfsUALm XHy/aQMuyb6gywGkFwoq+PHvI0Koe2wIOvjewOfV78A2eF/GnhNm6zFr1vFoFmnJ 4kVEMDTOoZ3qT9MfluB+ =c0wP -----END PGP SIGNATURE----- --v4cNTr+tRGSs1txX--