union fs

union fs

[RvP]

Hi,

Support for unionfs-modules with recent kernels is broken in oe, see
http://bugs.openembedded.org/show_bug.cgi?id=1189.

Are there plans to fix this?

Re: union fs

[Mike (mwester)]

RvP wrote:
> Hi,
> 
> Support for unionfs-modules with recent kernels is broken in oe, see
> http://bugs.openembedded.org/show_bug.cgi?id=1189.
> 
> Are there plans to fix this?

The unionfs modules are part of the 2.6 kernel now.  Do you really need 
them?

Unslung is the only distro AFAIK that is still based on a 2.4 kernel; 
and unionfs is not very useful (the obvious use, which is to use ntfs-3g 
to replace the buggy Linksys proprietary ntfs driver is not write-safe, 
and thus isn't useful).

I would suspect that we can simply drop the modules build from unionfs. 
  (But perhaps leave the recipe present in case someone else wants very 
much to try to get ntfs-3g working on unslung.)

Mike (mwester)

Re: union fs

[RvP]

From: "Mike (mwester)" <mwester@dls.net>
> RvP wrote:
> > Hi,
> > 
> > Support for unionfs-modules with recent kernels is broken in oe, see
> > http://bugs.openembedded.org/show_bug.cgi?id=1189.
> > 
> > Are there plans to fix this?
> 
> The unionfs modules are part of the 2.6 kernel now. 

Are they? I read on the unionfs site that they are part of the -mm tree as of
Jan. 2007, but, you're probably right. OpenWRT does use unionfs per default
with a 2.6.24 kernel.

> Do you really need them?

Not anymore, I was looking for a way to install extra pakages for SlugOS on
an external drive. I found in the docs that a copy of the complete rootfs can
be installed on an external drive using 'turnup' (NSLU2 specific tool). I'll
go that way.

Thanks,

Richard.

Re: union fs

[Mike (mwester)]

RvP wrote:
> From: "Mike (mwester)" <mwester@dls.net>
>> RvP wrote:
>>> Hi,
>>>
>>> Support for unionfs-modules with recent kernels is broken in oe, see
>>> http://bugs.openembedded.org/show_bug.cgi?id=1189.
>>>
>>> Are there plans to fix this?
>> The unionfs modules are part of the 2.6 kernel now. 
> 
> Are they? I read on the unionfs site that they are part of the -mm tree as of
> Jan. 2007, but, you're probably right. OpenWRT does use unionfs per default
> with a 2.6.24 kernel.

No, you're right - I looked more closely, it's still not made it into 
the 2.6.24 kernel.

>> Do you really need them?
> 
> Not anymore, I was looking for a way to install extra pakages for SlugOS on
> an external drive. I found in the docs that a copy of the complete rootfs can
> be installed on an external drive using 'turnup' (NSLU2 specific tool). I'll
> go that way.
> 
> Thanks,
> 
> Richard.

Cool.  Turnup is the right way to do it with SlugOS.  But I do still 
plan to get unionfs into the SlugOS feeds at some point.  It does look 
like at the moment that means fixing that recipe somehow; something that 
won't be simple (since the patch downloaded depends on the kernel 
version the recipe is being built for).

Thanks,
Mike (mwester)

Re: union fs

[Szabolcs Szakacsits]

Mike (mwester <mwester <at> dls.net> writes:
> 
> Unslung is the only distro AFAIK that is still based on a 2.4 kernel; 
> and unionfs is not very useful (the obvious use, which is to use ntfs-3g 
> to replace the buggy Linksys proprietary ntfs driver is not write-safe, 
> and thus isn't useful).
> 
> I would suspect that we can simply drop the modules build from unionfs. 
>   (But perhaps leave the recipe present in case someone else wants very 
> much to try to get ntfs-3g working on unslung.)

What do you mean ntfs-3g is not write safe? Nobody ever told us.

It's certainly used and certified on several ARM and MIPS embedded devices 
regularly.

Regards,  Szaka

--
NTFS-3G: http://ntfs-3g.org

Re: union fs

[Mike (mwester)]

Szabolcs Szakacsits wrote:

> What do you mean ntfs-3g is not write safe? Nobody ever told us.
> 
> It's certainly used and certified on several ARM and MIPS embedded devices 
> regularly.
> 
> Regards,  Szaka

According to the official docs, due to limitations of the fuse driver 
for 2.4 kernels, ntfs-3g on such old kernels is prone to data loss. 
This is a fuse problem, but effectively if you value your NTFS 
partition's consistency, it means that ntfs-3g on such old kernels 
should be read-only.

On 2.6, ntfs-3g works wonderfully on all the devices in read and write 
modes, and is the driver I recommend for NTFS support on the SlugOS 
(ARM) distro.

Sorry for not being more clear.

Mike (mwester)

Re: union fs

[Szabolcs Szakacsits]

Mike (mwester <mwester <at> dls.net> writes:
> 
> According to the official docs, due to limitations of the fuse driver 
> for 2.4 kernels, ntfs-3g on such old kernels is prone to data loss. 
> This is a fuse problem, but effectively if you value your NTFS 
> partition's consistency, it means that ntfs-3g on such old kernels 
> should be read-only.
> 
> On 2.6, ntfs-3g works wonderfully on all the devices in read and write 
> modes, and is the driver I recommend for NTFS support on the SlugOS 
> (ARM) distro.
> 
> Sorry for not being more clear.

I see, thank you for the explanation. I think we should have better documented 
this ntfs-3g issue, sorry about it.

Everything is as safe with the 2.4 kernels as with the 2.6 ones if after umount 
one makes sure that the ntfs-3g process is terminated before a device is 
detached or the box is powered down. This can be ensured automatic e.g. by a 
few shell commands. 

Regards,  Szaka

--
NTFS-3G: http://ntfs-3g.org