From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Sterba <dave@jikos.cz>
Subject: Re: Interpreting Output of "btrfs fi show"
Date: Thu, 26 Apr 2012 13:53:26 +0200
Message-ID: <20120426115326.GO20982@twin.jikos.cz>
References: <CAGy7UtioPbdjomzuv3phZcF+HShyYKytkOKnAhP+4VGj29Aahg@mail.gmail.com>
 <C7$h9m5PCXB@helmut.hullen.de>
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Cc: linux-btrfs@vger.kernel.org
To: helmut@hullen.de
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On Thu, Apr 26, 2012 at 01:11:00PM +0200, Helmut Hullen wrote:
> I now use to delete about the first 10 MByte of the target disk via "dd  
> if=/dev/zero"

FYI, the minimal amount of data you need to rewrite is 4k:

dd if=/dev/zero of=/dev/ice bs=1k count=4 seek=64

david