Re: Filesystem corruption MD (imsm) Raid0 via 2 SSD's + discard

[Holger Kiehl]

On Thu, 21 May 2015, NeilBrown wrote:

> On Thu, 21 May 2015 01:32:13 +0500 Roman Mamedov <rm@xxxxxxxxxxx> wrote:
>
> > On Wed, 20 May 2015 20:12:31 +0000 (UTC)
> > Holger Kiehl <Holger.Kiehl@xxxxxx> wrote:
> >
> > > The kernel I was running when I discovered the
> > > problem was 4.0.2 from kernel.org. However, after reinstalling from DVD
> > > I updated to Fedora's lattest kernel, which was 3.19.? (I do not remember
> > > the last numbers). So that kernel seems also effected, but I assume it
> > > contains many 'fixes' from 4.0.x. As filesystem I use ext4, distribution
> > > is Fedora 21 and hardware is: Xeon E3-1275, 16GB ECC Ram.
> > >
> > > My system seems to be now running stable for some days with kernel.org
> > > kernel 4.0.3 and with discard DISABLED. But I am still unsure what could
> > > be the real cause.
> >
> > It is a bug in the 4.0.2 kernel, fixed in 4.0.3.
> >
> > https://bugs.debian.org/cgi-bin/bugreport.cgi?bug=785672
> > https://bbs.archlinux.org/viewtopic.php?id=197400
> > https://kernel.googlesource.com/pub/scm/linux/kernel/git/stable/linux-stable/+/d2dc317d564a46dfc683978a2e5a4f91434e9711
>
> I suspect that is a different bug.
> I think this one is
>  https://bugzilla.kernel.org/show_bug.cgi?id=98501
Should there not be a big fat warning going around telling users to disable
discard on Raid 0 until this is fixed? This breaks the filesystem completely
and I believe there is absolutly no way one can get back the data.

Is this fixed in 4.0.4? And which kernels are effected? There could be many
people running systems that have not noticed this and don't know in what
dangerous situation they are when they delete data.

Regards,
Holger
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