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Subject: Re: ZFS - RAIDZ1 Recovery (Evgeny Sam)
To: "Kevin P. Neal" <kpn@neutralgood.org>, Evgeny Sam <esamorokov@gmail.com>
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Cc: freebsd-fs@freebsd.org
From: Willem Jan Withagen <wjw@digiware.nl>
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Date: Tue, 31 May 2016 12:15:04 +0200
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On 30-5-2016 22:21, Kevin P. Neal wrote:
> There are several good ways to duplicate a disk, and at the top of the
> list are tools known to the people you are going to need help from. That
> means using the 'dd' command to duplicate the entire disk including the
> GPT labels. Or use something from Polytropon's list posted to these lists
> (usually the questions list mostly) every so often.
> 
> The dd command when given the "conv=noerror,sync" option can be used to
> duplicate an entire disk. Then a ZFS scrub can correct the lost blocks.

Might I suggest dd_rescue here?

Sort of designed for precisely this problem.
Does large bulk transfers, but when in error it reduces blocksize to the
sector, and tries several times....
And there are lots of other options.

So it is fast and as accurate as it can get.

Save my life a few times.

--WjW