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Re: Geting rid of ide-scsi ?

> To summarize : using a stock kernel allows the use of /dev/hdx with
> dvd+rw-tools. Patching the kernel allows for true direct access to dvd+r(w)
>   discs, but needs ide-scsi on 2.4.x kernels (the stock 2.6.0 kernel
> already has the relevant "patch").
> Three questions :
> 1) Is the above summary correct ?

Not really. The very last assumption, namely "(the stock 2.6.0 kernel
already has the relevant "patch")," is wrong. User-land burning
applications, such as dvd+rw-tools, are currently the only way to
perform DVD recordings under 2.6. In other words there is no kernel
DVD+RW support for 2.6 yet (there is an explicit statement about this on
dvd+rw-tools page).

> 2) Is the 2.4 kernel patch compatible with the "packet writing" patch one
> can use to allow packet writing to CD, thus allowing to create and update
> R/W UDF filesystems (à la Adaptec DirectCD) ?

No, but there was work done in this direction, see
http://lists.debian.org/cdwrite/2003/cdwrite-200309/msg00061.html. See
also "Packet writing on NEC1300" thread at
http://lists.debian.org/cdwrite/2003/cdwrite-200309/threads.html for
background discussion.

> (The very same question may
> or may not be relevant for 2.6 kernels).

Answer for now is "no, period."

> 3) [ Out of my deep ignorance of DVD[+|-]R(W) standards ] : Is it possible
> to create such UDF R/W filesystems on DVDs ?

Yes (for DVD+RW), but consensus is that Linux UDF implementation is too
inefficient to be useful. To my knowledge most people who tried it,
adandoned it in favor of other solutions: growisofs -M or pre-mastering
a file system image in loopback mounted 4.38GB container and burning it
with growisofs -Z /dev/dvd=container.

> This could allow for a swell
> incremental backup system for small/medium systems ... As I understand it,
> growisofs currently allows for something like that (i.e. one can, for
> example, *add* an incremental tar archive to a disk already containing a
> tar archive).

Depends on what do you mean by "contain a tar archive." If you mean "an
isofs volume with tar archive," then yes, growisofs takes care of it(*).
But if you mean that media is tar-formatted, e.g. "tar cf - /some/dir |
growisofs -Z /dev/dvd=/dev/fd/0," then only next version will provide
for appending other tar archives (but you'll have a lot of calculations
to perform yourself!).

(*) with reservations for isofs implementation deficiencies, such as
2GB-1 file size limit, discussed multiple time on the list;

> The current "packet writing" tools allow for *replacing* an
> existing file on a CD. Is such a solution possible on a DVD ?

As already mentioned above, yes, but it's impractical. A.

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