On Sun, Jun 05, 2016 at 06:03:53PM +0200, Arne Jansen wrote:
> On 05/06/16 17:32, Pawel Jakub Dawidek wrote:
> > Unfortunately tools like photorec won't work (I assume the tool scans
> > the disk and looks for some JPEG headers, etc.) as this was RAIDZ1 pool,
> > so none of the disks contains recognizable data.
> 
> Are you sure? Isn't only the parity information unusable? So 2/3 of the
> information should be there in plain. It would be good to revive
> the broken disk, though.

Each ZFS block will be broken into two pieces. By default maximum block
size if 128kB, so on disk 0 you will find first, third, etc. 64kB chunk
of the photo. Enough to find a JPEG header, indeed, by photos are rather
larger.

> > Two questions come to my mind:
> > 1. Is it possible to recover the data now?
> > 2. Is it possible to recover the data in theory?
> >
> > I'm afraid the answer to the first question is 'no', because we are not
> > aware of any existing tools that could help you with the process and to
> > do it now you would need to find ZFS expert willing to spend some
> > serious amount of time, which I'm sure will cost a lot.
> >
> > But if I understand your description correctly, the data is still on the
> > disks, so in theory it should be possible to recover it. Maybe not now,
> > but in 5 years? 10 years? Family memories is probably not something you
> > need immediately and after some time someone may develop a tool to help
> > recover data from the pools like yours. Even if noone will, maybe you
> > will become rich enough (or maybe you are already, no idea) to sponsor
> > development of such a tool.
> 
> Writing such a tool would be fun, but it would probably take weeks to
> months to write it. The question is if there are enough broken pools to
> make it worth investing the time.

When I decided to port ZFS to FreeBSD my estimation was to have a
working rad-write prototype in 6 months. It took 10 days (and nights).
You won't be able to tell until you try:)

-- 
Pawel Jakub Dawidek                       http://www.wheelsystems.com
FreeBSD committer                         http://www.FreeBSD.org
Am I Evil? Yes, I Am!                     http://mobter.com

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