Which kernel do I need to use ext4 64-bit.

Which kernel do I need to use ext4 64-bit.

[Ram Ramesh]

I asked this question on linux-ext3 and apparently I cannot post it 
there as moderator has to approve it, and he is neither approving or 
disapproving my message. May be the list is dormant now and everything 
happens here. Any way here is my question.

> Is there a kernel version restriction for 64bit ext4 FS creation/use? 
> Google does not seem to find any info on this. I have mythbuntu  14.04 
> distro that has
>> zym [rramesh] 473 > uname -a
>> Linux zym 3.13.0-119-generic #166-Ubuntu SMP Wed May 3 12:18:55 UTC 
>> 2017 x86_64 x86_64 x86_64 GNU/Linux
> Can I create a 64bit ext4 under this kernel and mount/use?
>
> BTW, my resize2fs cannot grow the file system beyond 16TB. I assume 
> this is due to current FS being 32bit. I need to make it 64bit. What 
> is the best way to go about doing this *on my distro*?
>> zym [rramesh] 474 > resize2fs
>> resize2fs 1.42.9 (4-Feb-2014)
>> Usage: resize2fs [-d debug_flags] [-f] [-F] [-M] [-P] [-p] device 
>> [new_size]
>
> Ramesh 

Ramesh

Re: Which kernel do I need to use ext4 64-bit.

[Andreas Dilger]

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On Jul 16, 2017, at 10:26 AM, Ram Ramesh <rramesh2400@gmail.com> wrote:
> I asked this question on linux-ext3 and apparently I cannot post it there as moderator has to approve it, and he is neither approving or disapproving my message. May be the list is dormant now and everything happens here. Any way here is my question.

The linux-ext3 list is obsolete, linux-ext4 is the right list for such questions.

>> Is there a kernel version restriction for 64bit ext4 FS creation/use? Google does not seem to find any info on this. I have mythbuntu  14.04 distro that has
>> 
>>> zym [rramesh] 473 > uname -a
>>> Linux zym 3.13.0-119-generic #166-Ubuntu SMP Wed May 3 12:18:55 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux
>> 
>> Can I create a 64bit ext4 under this kernel and mount/use?

The 64bit feature flag was only set for large filesystems (> 16TB) in the past,
but I believe that this is the default for all filesystems since e2fsprogs-1.43.

>> BTW, my resize2fs cannot grow the file system beyond 16TB. I assume this is due to current FS being 32bit. I need to make it 64bit. What is the best way to go about doing this *on my distro*?
>> 
>>> zym [rramesh] 474 > resize2fs
>>> resize2fs 1.42.9 (4-Feb-2014)
>>> Usage: resize2fs [-d debug_flags] [-f] [-F] [-M] [-P] [-p] device [new_size]

This is fairly old.  1.42.13 is probably the better version for you to use.
I believe that 1.43 also has support for enabling the 64bit feature on an
existing filesystem.

Cheers, Andreas






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Re: Which kernel do I need to use ext4 64-bit.

[Ram Ramesh]

On 07/18/2017 02:17 PM, Andreas Dilger wrote:
> On Jul 16, 2017, at 10:26 AM, Ram Ramesh <rramesh2400@gmail.com> wrote:
>> I asked this question on linux-ext3 and apparently I cannot post it there as moderator has to approve it, and he is neither approving or disapproving my message. May be the list is dormant now and everything happens here. Any way here is my question.
> The linux-ext3 list is obsolete, linux-ext4 is the right list for such questions.
>
>>> Is there a kernel version restriction for 64bit ext4 FS creation/use? Google does not seem to find any info on this. I have mythbuntu  14.04 distro that has
>>>
>>>> zym [rramesh] 473 > uname -a
>>>> Linux zym 3.13.0-119-generic #166-Ubuntu SMP Wed May 3 12:18:55 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux
>>> Can I create a 64bit ext4 under this kernel and mount/use?
> The 64bit feature flag was only set for large filesystems (> 16TB) in the past,
> but I believe that this is the default for all filesystems since e2fsprogs-1.43.
>
>>> BTW, my resize2fs cannot grow the file system beyond 16TB. I assume this is due to current FS being 32bit. I need to make it 64bit. What is the best way to go about doing this *on my distro*?
>>>
>>>> zym [rramesh] 474 > resize2fs
>>>> resize2fs 1.42.9 (4-Feb-2014)
>>>> Usage: resize2fs [-d debug_flags] [-f] [-F] [-M] [-P] [-p] device [new_size]
> This is fairly old.  1.42.13 is probably the better version for you to use.
> I believe that 1.43 also has support for enabling the 64bit feature on an
> existing filesystem.
>
> Cheers, Andreas
>
>
>
>
>
Thanks. I can't update e2fsprogs to 1.43 without knowing that the file 
system it creates can be mounted on my kernel. I am with ubuntu 14.04 
which only has these. I could manually download and build from source or 
install from another repository only if I know my kernel will support 
it. So, I really need to know if linux 3.13 support ext4-64bit.

Ramesh

Re: Which kernel do I need to use ext4 64-bit.

[Andreas Dilger]

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On Jul 18, 2017, at 4:49 PM, Ram Ramesh <rramesh2400@gmail.com> wrote:
> 
> On 07/18/2017 02:17 PM, Andreas Dilger wrote:
>> On Jul 16, 2017, at 10:26 AM, Ram Ramesh <rramesh2400@gmail.com> wrote:
>>> I asked this question on linux-ext3 and apparently I cannot post it there as moderator has to approve it, and he is neither approving or disapproving my message. May be the list is dormant now and everything happens here. Any way here is my question.
>> The linux-ext3 list is obsolete, linux-ext4 is the right list for such questions.
>> 
>>>> Is there a kernel version restriction for 64bit ext4 FS creation/use? Google does not seem to find any info on this. I have mythbuntu  14.04 distro that has
>>>> 
>>>>> zym [rramesh] 473 > uname -a
>>>>> Linux zym 3.13.0-119-generic #166-Ubuntu SMP Wed May 3 12:18:55 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux
>>>> Can I create a 64bit ext4 under this kernel and mount/use?
>> The 64bit feature flag was only set for large filesystems (> 16TB) in the past,
>> but I believe that this is the default for all filesystems since e2fsprogs-1.43.
>> 
>>>> BTW, my resize2fs cannot grow the file system beyond 16TB. I assume this is due to current FS being 32bit. I need to make it 64bit. What is the best way to go about doing this *on my distro*?
>>>> 
>>>>> zym [rramesh] 474 > resize2fs
>>>>> resize2fs 1.42.9 (4-Feb-2014)
>>>>> Usage: resize2fs [-d debug_flags] [-f] [-F] [-M] [-P] [-p] device [new_size]
>> This is fairly old.  1.42.13 is probably the better version for you to use.
>> I believe that 1.43 also has support for enabling the 64bit feature on an
>> existing filesystem.
>> 
> Thanks. I can't update e2fsprogs to 1.43 without knowing that the file system it creates can be mounted on my kernel. I am with ubuntu 14.04 which only has these. I could manually download and build from source or install from another repository only if I know my kernel will support it. So, I really need to know if linux 3.13 support ext4-64bit.

This is hard to know for sure with vendor kernels, as they may have applied patches that added features.  It is possible for you to either check the source for your kernel, or just try formatting a test filesystem with "-O 64bit" and mounting it.

Cheers, Andreas



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Re: Which kernel do I need to use ext4 64-bit.

[Theodore Ts'o]

On Tue, Jul 18, 2017 at 05:49:31PM -0500, Ram Ramesh wrote:
> Thanks. I can't update e2fsprogs to 1.43 without knowing that the file
> system it creates can be mounted on my kernel. I am with ubuntu 14.04 which
> only has these. I could manually download and build from source or install
> from another repository only if I know my kernel will support it. So, I
> really need to know if linux 3.13 support ext4-64bit.

Why are you not willing to update to Ubuntu 16.04, or something less
ancient?  The 64-bit feature is "supported" in the sense that the
kernel will understand it.  But if you have a paid support contract
from Canonical, you need to ask them if they will "support" it.  And
if you are hoping that the upstream kernel development community will
provide you free "support" for an ancient enterprise distribution, you
need to understand that this is best efforts only.

Technically speaking it appears that Linux 3.13 understands the 64-bit
feature.  Whether there are any critical bugs that have since been
fixed is a very different question.  Technically speaking, e2fsprogs
1.42.9 also understands the 64-bit feature, but I *know* that there
are a number of off-line resize bugs with the 64-bit features in the
1.42.x e2fsprogs line.

The reason to use 1.43.x is that it will turn on the 64-bit feature
"automatically".  But you could just also reformat the file system
using "mke2fs -t ext4 -O 64bit /dev/xxx" using 1.42.x.  Also note that
depending on which repository that you download e2fsprogs 1.43.x, you
may need to edit /etc/mke2fs.conf so mke2fs doesn't enable the
metadata_csum feature by default (which will not be supported by Linux
3.13).

So it might be that the safer thing to do is to build e2fsprogs 1.43.x
(so you get the latest bug fixes), and then check the /etc/mke2fs.conf
file to make sure it will create the same sort of file system as 1.42.x.

But if this is a critical enterprise/production system, and you are
expecting support by sending e-mail to linux-ext4@vger.kernel.org, I
do feel morally bound to dissuade you from doing that unless you are
prepared to carry most of the support burden yourself.  There is a
reason why companies pay $$$ to Red Hat or SuSE...

Cheers,

						- Ted

Re: Which kernel do I need to use ext4 64-bit.

[Ram Ramesh]

On 07/18/2017 06:31 PM, Theodore Ts'o wrote:
> On Tue, Jul 18, 2017 at 05:49:31PM -0500, Ram Ramesh wrote:
>> Thanks. I can't update e2fsprogs to 1.43 without knowing that the file
>> system it creates can be mounted on my kernel. I am with ubuntu 14.04 which
>> only has these. I could manually download and build from source or install
>> from another repository only if I know my kernel will support it. So, I
>> really need to know if linux 3.13 support ext4-64bit.
> Why are you not willing to update to Ubuntu 16.04, or something less
> ancient?  The 64-bit feature is "supported" in the sense that the
> kernel will understand it.  But if you have a paid support contract
> from Canonical, you need to ask them if they will "support" it.  And
> if you are hoping that the upstream kernel development community will
> provide you free "support" for an ancient enterprise distribution, you
> need to understand that this is best efforts only.
>
> Technically speaking it appears that Linux 3.13 understands the 64-bit
> feature.  Whether there are any critical bugs that have since been
> fixed is a very different question.  Technically speaking, e2fsprogs
> 1.42.9 also understands the 64-bit feature, but I *know* that there
> are a number of off-line resize bugs with the 64-bit features in the
> 1.42.x e2fsprogs line.
>
> The reason to use 1.43.x is that it will turn on the 64-bit feature
> "automatically".  But you could just also reformat the file system
> using "mke2fs -t ext4 -O 64bit /dev/xxx" using 1.42.x.  Also note that
> depending on which repository that you download e2fsprogs 1.43.x, you
> may need to edit /etc/mke2fs.conf so mke2fs doesn't enable the
> metadata_csum feature by default (which will not be supported by Linux
> 3.13).
>
> So it might be that the safer thing to do is to build e2fsprogs 1.43.x
> (so you get the latest bug fixes), and then check the /etc/mke2fs.conf
> file to make sure it will create the same sort of file system as 1.42.x.
>
> But if this is a critical enterprise/production system, and you are
> expecting support by sending e-mail to linux-ext4@vger.kernel.org, I
> do feel morally bound to dissuade you from doing that unless you are
> prepared to carry most of the support burden yourself.  There is a
> reason why companies pay $$$ to Red Hat or SuSE...
>
> Cheers,
>
> 						- Ted
Thanks for the details. Sorry, if I asked inappropriate questions that 
angered/annoyed any one. I thought I was simply checking with the 
experts. Andreas told me a simple method is to create a filesystem and 
test it. I was too dumb to think of that method first, instead of asking.

I am with 14.04 because it is supposed to be LTS and last time I changed 
too quickly (that is from 12.04 to 14.00, I had everything fall apart 
due to various release bugs) This time I am letting 16.04 chill a bit 
before switching. I would have done it earlier, but that too does not 
have efs2progs 1.43. Only 16.10 has. That is too hot for me.

This is my personal system for running DVR with mythtv. No enterprise 
here and no $$$ here either. Just some one willing to ask questions when 
needed.

Ramesh

Re: Which kernel do I need to use ext4 64-bit.

[Ram Ramesh]

On 07/18/2017 05:57 PM, Andreas Dilger wrote:
> On Jul 18, 2017, at 4:49 PM, Ram Ramesh <rramesh2400@gmail.com> wrote:
>> On 07/18/2017 02:17 PM, Andreas Dilger wrote:
>>> On Jul 16, 2017, at 10:26 AM, Ram Ramesh <rramesh2400@gmail.com> wrote:
>>>> I asked this question on linux-ext3 and apparently I cannot post it there as moderator has to approve it, and he is neither approving or disapproving my message. May be the list is dormant now and everything happens here. Any way here is my question.
>>> The linux-ext3 list is obsolete, linux-ext4 is the right list for such questions.
>>>
>>>>> Is there a kernel version restriction for 64bit ext4 FS creation/use? Google does not seem to find any info on this. I have mythbuntu  14.04 distro that has
>>>>>
>>>>>> zym [rramesh] 473 > uname -a
>>>>>> Linux zym 3.13.0-119-generic #166-Ubuntu SMP Wed May 3 12:18:55 UTC 2017 x86_64 x86_64 x86_64 GNU/Linux
>>>>> Can I create a 64bit ext4 under this kernel and mount/use?
>>> The 64bit feature flag was only set for large filesystems (> 16TB) in the past,
>>> but I believe that this is the default for all filesystems since e2fsprogs-1.43.
>>>
>>>>> BTW, my resize2fs cannot grow the file system beyond 16TB. I assume this is due to current FS being 32bit. I need to make it 64bit. What is the best way to go about doing this *on my distro*?
>>>>>
>>>>>> zym [rramesh] 474 > resize2fs
>>>>>> resize2fs 1.42.9 (4-Feb-2014)
>>>>>> Usage: resize2fs [-d debug_flags] [-f] [-F] [-M] [-P] [-p] device [new_size]
>>> This is fairly old.  1.42.13 is probably the better version for you to use.
>>> I believe that 1.43 also has support for enabling the 64bit feature on an
>>> existing filesystem.
>>>
>> Thanks. I can't update e2fsprogs to 1.43 without knowing that the file system it creates can be mounted on my kernel. I am with ubuntu 14.04 which only has these. I could manually download and build from source or install from another repository only if I know my kernel will support it. So, I really need to know if linux 3.13 support ext4-64bit.
> This is hard to know for sure with vendor kernels, as they may have applied patches that added features.  It is possible for you to either check the source for your kernel, or just try formatting a test filesystem with "-O 64bit" and mounting it.
>
> Cheers, Andreas
>
>
I am too dumb. I should have thought of the above method. You live and 
learn. Thanks for not ignoring me over silly questions.

Ramesh