From owner-freebsd-usb@FreeBSD.ORG Fri Nov 19 20:46:57 2010 Return-Path: Delivered-To: freebsd-usb@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 9D6D1106564A for ; Fri, 19 Nov 2010 20:46:57 +0000 (UTC) (envelope-from guru@unixarea.de) Received: from ms16-1.1blu.de (ms16-1.1blu.de [89.202.0.34]) by mx1.freebsd.org (Postfix) with ESMTP id 2768A8FC1B for ; Fri, 19 Nov 2010 20:46:56 +0000 (UTC) Received: from [109.41.253.170] (helo=tiny.Sisis.de.) by ms16-1.1blu.de with esmtpsa (TLS-1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.69) (envelope-from ) id 1PJXr8-0000VG-On; Fri, 19 Nov 2010 21:46:51 +0100 Received: from tiny.Sisis.de. (localhost [127.0.0.1]) by tiny.Sisis.de. (8.14.3/8.14.3) with ESMTP id oAJKkhYK001534; Fri, 19 Nov 2010 21:46:44 +0100 (CET) (envelope-from guru@unixarea.de) Received: (from guru@localhost) by tiny.Sisis.de. (8.14.3/8.14.3/Submit) id oAJKkeXQ001533; Fri, 19 Nov 2010 21:46:40 +0100 (CET) (envelope-from guru@unixarea.de) X-Authentication-Warning: tiny.Sisis.de.: guru set sender to guru@unixarea.de using -f Date: Fri, 19 Nov 2010 21:46:39 +0100 From: Matthias Apitz To: Warren Block Message-ID: <20101119204639.GA1521@tiny.Sisis.de> References: <20101119143337.GA3023@current.Sisis.de> <201011191821.09308.hselasky@c2i.net> <20101119173519.GA3933@current.Sisis.de> <201011191916.53655.hselasky@c2i.net> <20101119183900.GA1221@tiny.Sisis.de> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Operating-System: FreeBSD 8.0-CURRENT (i386) User-Agent: Mutt/1.5.19 (2009-01-05) X-Con-Id: 51246 X-Originating-IP: 109.41.253.170 Cc: freebsd-usb@freebsd.org Subject: Re: copying /dev/da0 with dd(1) to file: output differs X-BeenThere: freebsd-usb@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: Matthias Apitz List-Id: FreeBSD support for USB List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Fri, 19 Nov 2010 20:46:57 -0000 El día Friday, November 19, 2010 a las 12:39:13PM -0700, Warren Block escribió: > > Just an idea: The USB key in question was new and I only created the > > file system on it the usual way (fdisk, bsdlabel, newfs). Then I > > restored the dump on it (which took 26 hours for 3.1 GByte dump file). > > The USB key boots fine, btw. > > 26 *hours*? USB 1.1? I don't think so. It is the Acer One D250 netbook. > Well, they could be anything. But the original filesystem has > formerly-used blocks with old data from deleted files. dump doesn't > copy those, but dd does. > > > Should I overwrite the full USB key from /dev/zero? > > Possibly there would still be differences. Filesystem metadata like > date last mounted, for example. If you want a block-by-block duplicate, > the brute-force method is to just dd the whole drive. Use bs=64k or > bs=1m to help reduce overhead. Warren, perhaps you missed my point. I have a prepared boot-able key and I want to give away a copy of it as a file on DVD. So I dd(1)'ed the key to disk and did this twice to ensure that the copy was fine, but the two files differ. How can I make sure that the file on disk (or DVD) is a exact copy of the key? matthias -- Matthias Apitz t +49-89-61308 351 - f +49-89-61308 399 - m +49-170-4527211 e - w http://www.unixarea.de/