Re: problems writing a large file to DVD+R Double Layer disk

[scdbackup@gmx.net]

Hi,

Joerg Schilling:
> The same could be said for e.g. growisofs. Growisofs artificially
> limits the write mode for DVDs to what DVD+R/RW allows ignoring the
> features of DVD-R/RW.

Indeed ? It writes blank DVD-R[W] as DAO with option -dvd-compat
and it writes them as Incremental Streaming (32 kB fixed packet)
elsewise. Reasons not to use Incremental Streaming with DVD-RW:
- they are formatted to Restricted Overwrite,
- they are fast-blanked, which allows DAO only.
Usually the media is left appendable after Incremental Streaming,
but on appendable DVD-RW growisofs -dvd-compat causes closing
after the session is written.


>  The size is only "unneded"
> in case you use the less compatible packet writing mode. Cdrecord
> by default implements the write mode with the best read-compatibility.

Do i miss something ? Is there a way to use
Incremental Streaming on DVD-R[W] via cdrecord ?
It would come in very handy for scdbackup.

Don't get me wrong. I am sincerely interested in learning
about cdrecord's capabilities.
I just tested with cdrecord-2.01.01a23 on a blank DVD-RW

  dd if=/dev/zero bs=1M count=500 | cdrecord -v dev=0,0,0 -packet -

and got 

  cdrecord: Drive does not support TAO recording.
  cdrecord: Illegal write mode for this drive.

The same with
  dd if=/dev/zero bs=1M count=500 | cdrecord -v dev=0,0,0 -tao -

With
  dd if=/dev/zero bs=1M count=500 | cdrecord -v dev=0,0,0 -
i get
  cdrecord: Track 1 has unknown length.
  cdrecord: Use tsize= option in SAO mode to specify track size.


Testing cdrskin on the very same media:
  dd if=/dev/zero bs=1M count=500 | cdrskin -v dev=0,0,0 - 
This works.
Also working:
  dd if=/dev/zero bs=1M count=500 | cdrskin -v dev=0,0,0 blank=all -multi -
  dd if=/dev/zero bs=1M count=500 | cdrskin -v dev=0,0,0 -multi -
producing two recognizable sessions on the media
which stays appendable:
  Media content: session  1  track     1 data   lba:         0    00:02:00
  Media content: session  1  leadout            lba:    256000    56:55:25
  Media content: session  2  track     2 data   lba:    284688    63:17:63
  Media content: session  2  leadout            lba:    540688   120:11:13
  Media msinfo : mkisofs ... -C 284688,548384
Much like on CD. Linux mount as of kernel 2.4 recognizes
the last session as the thing to mount (and to fail with,
in this case). One could use the -C values to produce
a third session in mountable ISO-9660 format.

If there is a way to do this with cdrecord on DVD-R[W] then
please give me an example how to.


> I advise to use cdrecord for production quality media...

Indeed my advise to write the single large file rawly
would match well the characteristics of cdrecord -sao :

  cdrecord -v dev=... -sao /my/large/file
 
This advise stays valid in case no other suitable formatting
can be found.


Have a nice day :)

Thomas