Re: Writing to DVD

[scdbackup@gmx.net]

Hi,

>>>   # tar -Mcvf /dev/cdrom /some/files
> This seems to work fine. I copied a 1.2 GB file to a DVD+RW using this
> method, and it verified OK. This technique gave an average data transfer
> rate of 3.1 MB/s.

I am thoroughly astonished.
... and pondering wether i should try this too ...
(I'm reluctant to do strange things with my system)


>> My approach would be
>>    tar cvzf - /some/files | \
>>     growisofs -use-the-force-luke -Z /dev/sr0=/proc/self/fd/0
>> 
>> (tar option -M is still a bit obscure to me after
>> reading man and info tar. Is it about end-of-tape
>> handling ?)
> 
> Although using growisofs in that manner is probably a more comaptible
> and reliable method, the main problem is that it can not readily split
> the image across multiple DVDs on-the-fly, as far as I am aware. The -M
> option of tar is to allow a tar file/stream to be split across multiple
> volumes. Thus when the end of a tape is reached, a new tape can be
> inserted and writing can continue. The M option appears to work when
> writing to DVD as well, although I haven't yet tried it with growisofs.
> Thus
>    # tar -Mcvf /dev/cdrom /some/files
> will split the tar file across multiple DVDs if necessary. It's a bit of
> a hack, but it seems to work.

This does astonish me even more.
To get an end-of-tape usable with tar ... you have a
miracle wonder /dev/cdrom in your system. 

There are projects like Paul Serice's shunt
  http://www.serice.net/shunt/
or my own one
  http://scdbackup.webframe.org
which deal with multi-volume backups on CD/DVD.
We both carefuly avoid to overflow the media
but divide the backup data into digestible pieces
in advance.

(In the most simple case one just needs a filter
program which stops writing before an overflow
occurs, asks for the next media and starts a new
run of growisofs.
Nevertheless it is desirable to get media which
are not totally dependent on each other.)


Does this trick work with CD-RW too ?


Does anybody know what makes it work ?
It looks like Andy's kernel patch
described on the dvd+rw-tools homepage
  http://fy.chalmers.se/~appro/linux/DVD+RW/


> Also I can't seem to get growisofs to
> write faster than 1x. But that's another problem altogether...

What DVD+RW media do you use ?
What does  dvd+rw-mediainfo  report ?
(You did try option speed=... , i presume)


Have a nice day :)

Thomas