Nilfs users (Log-Structured Snapshotting Filesystem)

Sven-Göran Bergh | 1 May 2012 12:38

Nilfs2 and Grub2

Hi list,

I have done some observations with the combination
grub2 and nilfs2 on the boot partition. It would
be valuable to know if anyone else has done similar
observations or if this is a {,/un}known problem.

After some harsh handling the system is rebooted
and grub2 hangs during stage 1.5-2. Once grub2 has
encountered this problem it is consistent. It will
hang on every consecutive boot.

However, if the filesystem (on a CF) is mounted by
another system there are no problems reported.
Furthermore, once the filesystem has been mounted
by another system grub2 has no problems booting it
again afterwards. There is no need to do anything
else with the fs than mounting it by another system
and then umount it again.
My preliminary analysis is:
 * Nilfs2 is left in a disturbed state, due to some
   rough handling (still unknown in detail).
 * A normal mount has no problem to recover the fs
   in such case.
 * Grub2 lacks some of the recovery features
   performed during a normal mount and will have
   problem reading files on the fs.

Currently I do not have a more exact description of
the problem. I still have to figure out exactly what

(Continue reading)

headers

Ryusuke Konishi | 3 May 2012 08:49

Re: Nilfs2 and Grub2

Hi,
On Tue, 1 May 2012 03:38:57 -0700 (PDT), Sven-Göran_Bergh wrote:
> Hi list,
> 
> I have done some observations with the combination
> grub2 and nilfs2 on the boot partition. It would
> be valuable to know if anyone else has done similar
> observations or if this is a {,/un}known problem.
> 
> 
> After some harsh handling the system is rebooted
> and grub2 hangs during stage 1.5-2. Once grub2 has
> encountered this problem it is consistent. It will
> hang on every consecutive boot.
> 
> However, if the filesystem (on a CF) is mounted by
> another system there are no problems reported.
> Furthermore, once the filesystem has been mounted
> by another system grub2 has no problems booting it
> again afterwards. There is no need to do anything
> else with the fs than mounting it by another system
> and then umount it again.
> My preliminary analysis is:
>  * Nilfs2 is left in a disturbed state, due to some
>    rough handling (still unknown in detail).
>  * A normal mount has no problem to recover the fs
>    in such case.
>  * Grub2 lacks some of the recovery features
>    performed during a normal mount and will have
>    problem reading files on the fs.

(Continue reading)

headers

Jiro SEKIBA | 4 May 2012 07:13

Re: Nilfs2 and Grub2

Hi,

I'm original author of the grub2 NILFS2 module.

Yes, it lacks roll back/forward or recovery to keep the boot loader simple.
It also prevent from unintentional boot, like old buggy kernel is used.

Aside from the way it works, the code itself is capable to boot from
any checkpoints.  It happens to choose the latest one.  The only thing
we need is the way to _choose_ the checkpoint from grub interface :(.

thanks

regards
--

-- 
Jiro SEKIBA <jir@...>

At Thu, 03 May 2012 15:49:04 +0900 (JST),
Ryusuke Konishi wrote:
> 
> Hi,
> On Tue, 1 May 2012 03:38:57 -0700 (PDT), Sven-Göran_Bergh wrote:
> > Hi list,
> > 
> > I have done some observations with the combination
> > grub2 and nilfs2 on the boot partition. It would
> > be valuable to know if anyone else has done similar
> > observations or if this is a {,/un}known problem.
> > 
> >

(Continue reading)