Messages in this thread | | | Date | Tue, 28 Feb 2006 20:14:12 +0100 (MET) | From | Jan Engelhardt <> | Subject | Re: [slightly OT] dvdrecord 0.3.1 -- and yes, dev=/dev/cdrom works ;) |
| |
>> 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. > I doubt that. 10% of a 4.3 GB disk are, well, roughly 430 MB, which would make df show 3.9 GB as mountpoint size, not 4.3 GB. [MB and GB are powers of 1024 here.]
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/
| |