Bug#728806: linux-image-3.2.0-4-amd64: btrfs reports checksum error, while md5sum shows same checksum on original and backup
On Tue, Nov 05, 2013 at 07:21:53PM +0100, Hans Yntema wrote:
> Package: src:linux
> Version: 3.2.51-1
> Severity: important
>
> Dear Maintainer,
> *** Please consider answering these questions, where appropriate ***
>
> I have a dedicated backup internal SATA HDD; (4TB, GPT), filled 70%. Btrfs on DM-Crypt; Backups are created with Dirvish, e.g., many hardlinked files.
> HDD Converted (yesterday) from ext4 to btrfs. Subsequently run scrub. Scrub reports checksum errors: (multiple, as it is a Dirvish backup)
Oh dear.
> Nov 4 20:40:50 ijntema-svr kernel: [254525.824034] btrfs: checksum error at logical 522774728704 on dev /dev/dm-2, sector 1021044392, root 5, inode 199230932,
> offset 2135773184, length 4096, links 87 (path: dvd/20131008-0114/tree/dvd-18+/Contact/VTS_01_1.VOB)
>
> However, when I run md5sum on the backup HDD VTS_01_1.VOB and on the original HDD VTS_01_1.VOB, the checksum is the same. In other words,
> backup equals original; hence how can btrfs report a checksum error?
[...]
It might be referring to metadata. I don't know.
I suggest you forget the whole idea of using btrfs, and make some new
backups using ext4. I don't believe btrfs in Linux 3.2 is a robust
filesystem, nor is it likely to be fixed by subsequent updates. I'm
sorry this hasn't been made clear.
Ben.
--
Ben Hutchings
Nothing is ever a complete failure; it can always serve as a bad example.
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