Re: CD-RW

Ben Fennema (bfennema@falcon.csc.calpoly.edu)
Sat, 22 May 1999 10:20:22 -0700 (PDT)

> In an article in mailing-lists.linux-kernel you wrote:
> > Is there anyone who would be willing to write kernel support for CD-RW ?
> > The CD-RW should be mountable just as any standard block device,
> > and the standard file commands (cp,mv,rm, etc.) should work without any
> > special program (other than the new kernel or module loaded).
>
> Work is already in progress on UDF for Linux...
> See http://trylinux.com/projects/udf/
>

But the fs is just one part of writing the a CD-RW.
Support for packet writing has to be added to the cdrom driver (or
something).

Otherwise pulling the same stunt as people have been doing for
DVD-RAM is possible, but you only get 83 meg on a disc.
(Formating a disc with 1 block/packet).

The udf spec specifies 32 blocks per packet, which gives 533 meg.

The key to (fixed) packet writing is you have to write the WHOLE packet
to disc if you plan to write any of the blocks in the packet to disc,
otherwise all the other blocks in the packet get filled in with 0's.

Also CD-RW doesn't support bad block relocation in the drive.
And if I remember correctly, CD-RW rewrites are closer to 1000 than
50,000.

Ben

Linux UDF - http://www.trylinux.com/projects/udf/index.html
Latest Is - udf-0.8.4 (http://www.csc.calpoly.edu/~bfennema/udf-0.8.4.tar.gz)

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