On Thu, Feb 27, 2014 at 04:07:06PM -0500, Josef Bacik wrote:

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On 02/27/2014 04:05 PM, Chris Murphy wrote:

quoted

User reports successfully formatting and using an ~18TB Btrfs
volume on hardware raid5 using i686 kernel for over a year, and
then suddenly the file system starts behaving weirdly:

https://urldefense.proofpoint.com/v1/url?u=http://www.mail-archive.com/linux-btrfs%40vger.kernel.org/msg31856.html&k=ZVNjlDMF0FElm4dQtryO4A%3D%3D%0A&r=cKCbChRKsMpTX8ybrSkonQ%3D%3D%0A&m=6eUt5RgBggFh930oFrH19iR4z%2BFVzT%2F0%2F4dYPt3g48U%3D%0A&s=5ac126734d7fa1d3238ab09a2ddc021a8dcc8fff7b022560a4d068be2de37c00



I think this is due to the kernel page cache address space being
16TB limited on 32-bit kernels, as mentioned by Dave Chinner in
this thread:

https://urldefense.proofpoint.com/v1/url?u=http://oss.sgi.com/pipermail/xfs/2014-February/034588.html&k=ZVNjlDMF0FElm4dQtryO4A%3D%3D%0A&r=cKCbChRKsMpTX8ybrSkonQ%3D%3D%0A&m=6eUt5RgBggFh930oFrH19iR4z%2BFVzT%2F0%2F4dYPt3g48U%3D%0A&s=3e45f9288e6a77bc1a24dded368802c2ab46b812bf59953f74d4ee1d4141f7d2

 So it sounds like it shouldn't be possible to mount a Btrfs volume
larger than 16TB on 32-bit kernels. This is consistent with ext4
and XFS which refuse to mount large file systems.

Well that's not good, I'll fix this up.  Thanks,

Well, don't go assuming there's a problem just because I made an
off-hand comment. i.e my comment was simply "maybe it hasn't been
tested", and not an assertion that there is a bug or a problem....

Cheers,

Dave.

-- 
Dave Chinner
david@fromorbit.com