Re: Help recovering an interrupted raid0 reshape

[NeilBrown <neilb@suse.de>]

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On Tue, 7 Apr 2015 16:24:35 -0700 "Jonathan Harker (Jesusaurus)"
<jesusaurus@gentlydownthe.net> wrote:

> On Tue, Apr 7, 2015 at 3:56 PM, NeilBrown <neilb@suse.de> wrote:
> >
> >
> > Hmm... I think I see the bug.  It should be easy enough to fix, but I'd like
> > to be able to test it.
> > Could you please:
> >
> >  mkdir /tmp/md.metadata
> >  mdadm --dump /tmp/md.metadata /dev/md/alpha /dev/md/beta /dev/md/gamma
> >  tar czSf /tmp/md.tgz /tmp/md.metadata
> >
> > and then send me /tmp/md.tgz, which should be tiny and contain just the
> > metadata from the array.
> 
> I'll send that to you once tar finishes.

Thanks.  And just as well I tested as there was another problem.
I think it is all fixed now.
If you:

 cd /tmp
 git clone git://neil.brown.name/mdadm
 cd mdadm
 make
 ./mdadm -A /dev/md124 --force -vvvv /dev/md/{alpha,beta,gamma}

it should assemble the array and continue the reshape.

When it finishes it will leave the array as degraded RAID4.
Simply:
  mdadm /dev/md125 --grow --level=0

and it will instantly become RAID0.

NeilBrown

> 
> >
> > [[the patch which introduced the problem has a description which starts
> >     "This is a bit of a hack and ..."
> >   Never accept hacks!
> > ]]
> 
> I've reviewed and accepted a few hacks in my day as well. Hopefully
> the cleanup isn't too ugly.
> Thanks again for looking into this.
> 


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