From owner-freebsd-questions@FreeBSD.ORG Mon May 24 07:30:44 2010 Return-Path: Delivered-To: freebsd-questions@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 68461106564A for ; Mon, 24 May 2010 07:30:44 +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 250788FC25 for ; Mon, 24 May 2010 07:30:43 +0000 (UTC) Received: from [93.104.99.31] (helo=current.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 1OGS7V-0002Mr-Ki; Mon, 24 May 2010 09:30:41 +0200 Received: from current.Sisis.de (current [127.0.0.1]) by current.Sisis.de (8.14.3/8.14.3) with ESMTP id o4O7UrFa002578; Mon, 24 May 2010 09:30:53 +0200 (CEST) (envelope-from guru@unixarea.de) Received: (from guru@localhost) by current.Sisis.de (8.14.3/8.14.3/Submit) id o4O7Uq6u002577; Mon, 24 May 2010 09:30:52 +0200 (CEST) (envelope-from guru@unixarea.de) X-Authentication-Warning: current.Sisis.de: guru set sender to guru@unixarea.de using -f Date: Mon, 24 May 2010 09:30:52 +0200 From: Matthias Apitz To: Doug Hardie Message-ID: <20100524073052.GA2510@current.Sisis.de> References: <76E02DE6-9A61-4D24-9638-ABB7418711D9@lafn.org> Mime-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <76E02DE6-9A61-4D24-9638-ABB7418711D9@lafn.org> User-Agent: Mutt/1.4.2.3i X-Operating-System: FreeBSD 8.0-CURRENT (i386) X-Con-Id: 51246 X-Originating-IP: 93.104.99.31 Cc: freebsd-questions - Subject: Re: Verifying a DVD X-BeenThere: freebsd-questions@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list Reply-To: Matthias Apitz List-Id: User questions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 24 May 2010 07:30:44 -0000 El día Sunday, May 23, 2010 a las 03:23:26PM -0700, Doug Hardie escribió: > I am periodically backing up a bunch of files to DVD. I use mkisofs to create the original image and growisofs to write it to a real DVD. However, at that point I want to verify that the write was successful. I tried using dd to read back in the DVD to a file. Its interesting that the bs parameter must be at least 2048 or dd complains about a parameter error. However, the big issues is that the original image file is shorter than the read file. The difference is 10240 bytes. This difference is the same for bs 2048, 10240, or 102400. It appears that dd is adding one last block. Is there a way to prevent this or remove that block?_______________________________________________ I think it isn't important how many blocks are on the DVD, but more important that a) all files area readable on the DVD and b) are MD5 identically with the original on the hard disk. That's why after burning a tree of files for backup to some DVD I use a combination of find+md5+sort+diff to verify the result. HIH matthias -- Matthias Apitz t +49-89-61308 351 - f +49-89-61308 399 - m +49-170-4527211 e - w http://www.unixarea.de/ ¡Ya basta! ¡Tropas de OTAN, fuera de Afghanistan! There's an end of it! NATO troups out of Afghanistan! Schluss jetzt endlich! NATO raus aus Afghanistan!