From owner-freebsd-chat@FreeBSD.ORG Sun Feb 14 20:33:52 2010 Return-Path: Delivered-To: freebsd-chat@freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34]) by hub.freebsd.org (Postfix) with ESMTP id 24FB91065739 for ; Sun, 14 Feb 2010 20:33:52 +0000 (UTC) (envelope-from mitchell@wyatt672earp.force9.co.uk) Received: from relay.pcl-ipout01.plus.net (relay.pcl-ipout01.plus.net [212.159.7.99]) by mx1.freebsd.org (Postfix) with ESMTP id B04A48FC1B for ; Sun, 14 Feb 2010 20:33:51 +0000 (UTC) X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: AvsEABHtd0vUnw4T/2dsb2JhbACbHXS7IoRbBA Received: from pih-relay06.plus.net ([212.159.14.19]) by relay.pcl-ipout01.plus.net with ESMTP; 14 Feb 2010 20:33:49 +0000 Received: from [81.174.214.116] (helo=81-174-214-116.pth-as7.dial.plus.net) by pih-relay06.plus.net with esmtp (Exim) id 1NglA4-0005zu-TD; Sun, 14 Feb 2010 20:33:49 +0000 From: Frank Mitchell To: staffslug@staffslug.org.uk, sc@mailman.lug.org.uk, freebsd-chat@freebsd.org Date: Sun, 14 Feb 2010 20:32:55 +0000 User-Agent: KMail/1.9.10 MIME-Version: 1.0 Content-Disposition: inline Message-Id: <201002142032.55807.mitchell@wyatt672earp.force9.co.uk> Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit X-Plusnet-Relay: 016e30f8570d1fe31b03b7b5e0455785 Cc: Subject: ISO Image dd To DVD+RW X-BeenThere: freebsd-chat@freebsd.org X-Mailman-Version: 2.1.5 Precedence: list List-Id: Non technical items related to the community List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Sun, 14 Feb 2010 20:33:52 -0000 Hi: Latest issue of Linux Format Mag gives you a DVD ISO Image for FreeBSD v8.0, which I happen to be interested in. I was also looking for an interesting use for my DVD+RW disks. I read somewhere you could "dd" straight from an ISO Image file to DVD+RW, though I couldn't remember where. Previously I thought you could put an Ext2 Filesystem on DVD+RW, which turned out to be wrong. It worked the first time I tried, but not the second. But this experiment with "dd" worked, though I'm still unsure about how to use some of the options properly. Basically (under Linux) I put: dd if=FreeBSD-8.iso of=/dev/sr1 ibs=512 obs=32768 conv=sync And my DVD+RW wrote okay, showing: 3986344+0 Records In 62286+1 Records Out Note that DVDs use 2048-byte Sectors like CDs, but they're handled in Error-Correcting Super-Blocks of 16. DVD+RW can write individual Sectors, but only by updating the entire Super-Block. My first attempt tried writing with a BlockSize of 2048, whereupon Drive /dev/sr1 sat there winding the disk back and forth, presumably writing every Super-Block 16 times over. With a total BlockSize of 32768 things went alot more smoothly. The 62286+1 Records Out are Super-Blocks with an extra one partially written. The original 3986344 Records were 512-byte Disk Blocks, which make a whole number of 2048-byte DVD Sectors, but not Super-Blocks. Then I wrote it back to a file so I could check the result using diff: dd if=/dev/sr1 of=CHECK.ISO bs=2048 count=996586 conv=notrunc Here it's okay to read the DVD as 2048-byte Sectors, because they're individually addressable. You need the count to stop the entire DVD getting imaged, all 4.7 GB, which happened the first time I tried. And of course it's the count of 2048-byte Sectors, which is 3986344/4. CHECK.ISO was identical to the original Iso Image, and I was able to use the DVD+RW to install FreeBSD v8.0. Which left me with the same Xorg Configuration problems as FreeBSD v7.2, but that's another story... Faictz Ce Que Vouldras: Frank Mitchell