>From: Andy Polyakov <[EMAIL PROTECTED]> >> > Only once fully formated (which >> >takes 1 hour for 1x media), DVD-RW permits for random write, but with >> >32KB granularity. Latter means that you either have to have special >> >kernel driver which would arrange for 32KB granularity or modify file >> >system code to do same thing. Now note that no work (at least no visible >> >outcome so far) has been done to accomplish either of these two >> >alternatives under Linux (or any other Unix implementation), [presumaly] >> >because it's damn hard. >> >> So DVD+RW drives do things in firmware what you need to do in the kernel >> if you like to have 2k granularity with DVD-RW. But this is nothing a new >> firmware could not support.
>Specifications are very explicit about I/O granularity in DVD-RW >Restricted Overwrite mode. You seem to be willing to bend standard to >suit you, it's not fair play. Secondly it doesn't really matter what one >*could* *possibly* do [to stretch something to something else], does it? Well, it seems that you make unproven assumptions on the quality of DVD+, so I believe that it is fair to tell people that in theory it would be possible to enhance DVD- firmware and hardware so partially formatted media may be adddressed ramdomly. >> Note that the kernel also first reads a 512 byte sector from a hard disk >> if you like to write only 64 bytes. >Yes. But as already implied, if you want to extend this to 32KB to >accomodate DVD-RW Restricted Overwrite, you have to modify kernel file >system driver. The question was "why is there random access possibility >for DVD+RW, but not for DVD-RW?" A. If you believe that the kernel filesystem driver needs to be modified, then you are taling about a broken OS. On a typical OS, the filesystem code talks to the block abstraction layer. This layer has been the buffer case on historic implementation and is the semgment driver layer + VM Cache in modern implementations. What you have to do is to change this layer to know that there may be 32 KB Blocks..... Jörg -- EMail:[EMAIL PROTECTED] (home) Jörg Schilling D-13353 Berlin [EMAIL PROTECTED] (uni) If you don't have iso-8859-1 [EMAIL PROTECTED] (work) chars I am J"org Schilling URL: http://www.fokus.fraunhofer.de/usr/schilling ftp://ftp.berlios.de/pub/schily