From: Hugo Mills <hugo@carfax.org.uk>
To: Marc MERLIN <marc@merlins.org>
Cc: linux-btrfs <linux-btrfs@vger.kernel.org>
Subject: Re: BTRFS: read error corrected: ino 1 off 226840576 (dev /dev/mapper/dshelf1 sector 459432)
Date: Wed, 17 Jun 2015 10:11:21 +0000 [thread overview]
Message-ID: <20150617101121.GQ9850@carfax.org.uk> (raw)
In-Reply-To: <20150617071654.GI16468@merlins.org>
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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 |
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next prev parent reply other threads:[~2015-06-17 10:11 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-17 7:16 BTRFS: read error corrected: ino 1 off 226840576 (dev /dev/mapper/dshelf1 sector 459432) Marc MERLIN
2015-06-17 10:11 ` Hugo Mills [this message]
2015-06-17 10:58 ` Sander
2015-06-17 11:01 ` Hugo Mills
2015-06-17 16:19 ` Marc MERLIN
2015-06-18 4:32 ` Duncan
2015-06-17 13:51 ` Duncan
2015-06-17 14:58 ` Chris Murphy
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