Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932415AbWB1TAE (ORCPT ); Tue, 28 Feb 2006 14:00:04 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S932416AbWB1TAB (ORCPT ); Tue, 28 Feb 2006 14:00:01 -0500 Received: from iriserv.iradimed.com ([69.44.168.233]:59928 "EHLO iradimed.com") by vger.kernel.org with ESMTP id S932415AbWB1TAB (ORCPT ); Tue, 28 Feb 2006 14:00:01 -0500 Message-ID: <44049D5A.1010806@cfl.rr.com> Date: Tue, 28 Feb 2006 13:58:34 -0500 From: Phillip Susi User-Agent: Thunderbird 1.5 (Windows/20051201) MIME-Version: 1.0 To: Jan Engelhardt CC: Sam Vilain , Luke-Jr , Jesper Juhl , Bernhard Rosenkraenzer , linux-kernel@vger.kernel.org Subject: Re: [slightly OT] dvdrecord 0.3.1 -- and yes, dev=/dev/cdrom works ;) References: <200602250042.51677.bero@arklinux.org> <200602261330.15709.luke@dashjr.org> <9a8748490602260529h3a2890bhce4112feefb7cb1f@mail.gmail.com> <200602261339.13821.luke@dashjr.org> <440240F8.3010207@vilain.net In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit X-OriginalArrivalTime: 28 Feb 2006 19:01:55.0375 (UTC) FILETIME=[71374BF0:01C63C99] X-TM-AS-Product-Ver: SMEX-7.2.0.1122-3.52.1006-14295.000 X-TM-AS-Result: No--10.100000-5.000000-31 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2483 Lines: 52 Jan Engelhardt wrote: > Yes. A 650 MB *CD*-RW (DVD-RW too?) formatted in packet mode only has like > 500-something megabytes to allow for the sort of seeks required. > On DVD+RW, you get the full 4.3 GB (4.7 gB) AFAICS. > DVD-RAM physically is formatted like a hard disk. It is broken up into zones that hold different numbers of sectors which are individually and randomly read/writable. CD/DVD+-RW media is organized as a single long groove that consists of an unbroken series of large blocks composed of small blocks with user and control data interleaved and error corrected. It is for this reason that historically it could only be recorded from start to finish in one pass. There are two modern techniques to allow pseudo random write access for all forms of CD/DVD +/- RW media. These are packet mode, and mount rainier mode. MRW mode formats the disk into 32 KB blocks made up of 2048 byte sectors which are individually writable as far as the OS knows, because an MRW compliant drive is required to internally handle any required read/modify/write cycles to update the 32 KB blocks. MRW mode also reserves some of the disk for sector sparing which the drive firmware also handles. MRW mode is typically used on dvd+rw media. IIRC, this format typically "wastes" about 10% of the capacity of the medium. The other technique is packet mode. Packet mode formats the media into packets of sectors and each packet can be randomly rewritten. The current default size is only 32 sectors per packet. Each packet has 7 sectors of linking loss so around 18% of the disk space is wasted. I recently submitted a patch to pktcdvd and have some patches to the udftools package to support larger packet sizes. A packet size of 128 sectors reduces the waste to only 5.2%. >> DVD+RW, on the other hand, I just thought was a different surface technology >> (more expensive, higher quality) than DVD-RW. There is nothing to help with >> the lead-in/lead-out problem that is why you have several megabytes of lead-in >> and lead-out per session on a multi-session disc. >> >> But maybe I'm wrong here... if I could use a DVD+RW like a DVD-RAM I'd be very >> happy indeed. >> >> Sam. >> >> > > Jan Engelhardt - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/