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Date: Wed, 23 Apr 2014 11:18:52 +0200
From: Hugo Lombard <hal@elizium.za.net>
To: Gennadiy Gulchin <ggulchin@icloud.com>
Subject: Re: ZFS unable to import pool
Message-ID: <20140423091852.GH2830@sludge.elizium.za.net>
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On Wed, Apr 23, 2014 at 10:00:56AM +0200, Hugo Lombard wrote:
> On Wed, Apr 23, 2014 at 12:48:16AM -0700, Gennadiy Gulchin wrote:
> > Sorry, it was dd if=/dev/null of=/dev/ada7 bs=512 count=1...
> > 
> 
> OK, so you only overwrote the first 512 bytes of the disk, am I
> understanding correctly?
> 

Are you sure that the above command was the only command that altered
the data on ada7 outside of ZFS?

I tried to recreate your situation using file backed md devices, and
even when I deleted the first 256k of the one device (equivalent to an
entire label), zpool import could still see the device (and be willing
to import it) and zdb would show the first label as 'failed to unpack'
but would happily read the second (being+256k), third (end-512k), and
fourth (end-256k) labels.

Also, I might be on an entirely wrong track here...

-- 
Hugo Lombard
   .___.
   (o,o)
   /)  )
 ---"-"---