* BUG: >16TB Btrfs volumes are mountable on 32 bit kernels
@ 2014-02-27 21:05 Chris Murphy
2014-02-27 21:07 ` Josef Bacik
0 siblings, 1 reply; 5+ messages in thread
From: Chris Murphy @ 2014-02-27 21:05 UTC (permalink / raw)
To: Btrfs BTRFS
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:
http://www.mail-archive.com/linux-btrfs@vger.kernel.org/msg31856.html
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:
http://oss.sgi.com/pipermail/xfs/2014-February/034588.html
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.
Chris Murphy
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: BUG: >16TB Btrfs volumes are mountable on 32 bit kernels
2014-02-27 21:05 BUG: >16TB Btrfs volumes are mountable on 32 bit kernels Chris Murphy
@ 2014-02-27 21:07 ` Josef Bacik
2014-02-27 21:13 ` Chris Murphy
2014-02-28 4:38 ` Dave Chinner
0 siblings, 2 replies; 5+ messages in thread
From: Josef Bacik @ 2014-02-27 21:07 UTC (permalink / raw)
To: Chris Murphy, Btrfs BTRFS
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Hash: SHA1
On 02/27/2014 04:05 PM, Chris Murphy wrote:
> 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,
Josef
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^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: BUG: >16TB Btrfs volumes are mountable on 32 bit kernels
2014-02-27 21:07 ` Josef Bacik
@ 2014-02-27 21:13 ` Chris Murphy
2014-02-28 4:38 ` Dave Chinner
1 sibling, 0 replies; 5+ messages in thread
From: Chris Murphy @ 2014-02-27 21:13 UTC (permalink / raw)
To: Josef Bacik; +Cc: Btrfs BTRFS
On Feb 27, 2014, at 2:07 PM, Josef Bacik <jbacik@fb.com> wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> On 02/27/2014 04:05 PM, Chris Murphy wrote:
>> 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,
Is it a valid or goofy work around to partition this 21TB volume into two equal portions, and then:
mkfs.btrfs -d single -m raid1 /dev/sdb[12]
Maybe it's too much of an edge case to permit it even if it worked?
Chris Murphy
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: BUG: >16TB Btrfs volumes are mountable on 32 bit kernels
2014-02-27 21:07 ` Josef Bacik
2014-02-27 21:13 ` Chris Murphy
@ 2014-02-28 4:38 ` Dave Chinner
2014-02-28 13:05 ` Josef Bacik
1 sibling, 1 reply; 5+ messages in thread
From: Dave Chinner @ 2014-02-28 4:38 UTC (permalink / raw)
To: Josef Bacik; +Cc: Chris Murphy, Btrfs BTRFS
On Thu, Feb 27, 2014 at 04:07:06PM -0500, Josef Bacik wrote:
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> On 02/27/2014 04:05 PM, Chris Murphy wrote:
> > 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
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: BUG: >16TB Btrfs volumes are mountable on 32 bit kernels
2014-02-28 4:38 ` Dave Chinner
@ 2014-02-28 13:05 ` Josef Bacik
0 siblings, 0 replies; 5+ messages in thread
From: Josef Bacik @ 2014-02-28 13:05 UTC (permalink / raw)
To: Dave Chinner; +Cc: Chris Murphy, Btrfs BTRFS
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On 02/27/2014 11:38 PM, Dave Chinner wrote:
> On Thu, Feb 27, 2014 at 04:07:06PM -0500, Josef Bacik wrote:
>> -----BEGIN PGP SIGNED MESSAGE----- Hash: SHA1
>>
>> On 02/27/2014 04:05 PM, Chris Murphy wrote:
>>> 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....
>
If I can't take your word as gospel then my whole life has been a lie!
I'll look into it some more then but I seem to remember this being a
real problem, like we'd wrap around in pagecache once we went above
16tb, which would cause problems for metadata since our btree inode is
mapped logically to the entire fs. Thanks,
Josef
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^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2014-02-28 13:05 UTC | newest]
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2014-02-27 21:05 BUG: >16TB Btrfs volumes are mountable on 32 bit kernels Chris Murphy
2014-02-27 21:07 ` Josef Bacik
2014-02-27 21:13 ` Chris Murphy
2014-02-28 4:38 ` Dave Chinner
2014-02-28 13:05 ` Josef Bacik
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