backing up dvds

[Manolis Kiagias]

Roland Smith wrote:
> On Sat, Jun 30, 2007 at 05:39:29PM -0500, Jonathan Horne wrote:
>   
>> On Saturday 30 June 2007 16:46:36 Dave wrote:
>>     
>>> Hello,
>>>     I've got a 6.2 box with a dvd writer in it. I want to back up some dvds
>>> to iso files so i can recreate the dvds at a later time should it be
>>> needed. I can use dvdbackup to backup in to a directory structure, but i'd
>>> rather not mount, create the directory, and iso, i'd rather make the iso
>>> directly from the dvd. Any pointers on this?
>>> Thanks.
>>> Dave.
>>>       
>> dd if=/dev/acd0 of=/path/to/filename.iso bs=1024
>>     
>
> That should be bs=2048.
>
> AFAIK, data CDs and DVDs have 2k blocks:
>
> slackbox:~/tmp$ dd if=/dev/cd1 of=foo.dvd bs=1024
> dd: /dev/cd1: Invalid argument
> 0+0 records in
> 0+0 records out
> 0 bytes transferred in 0.000146 secs (0 bytes/sec)
>
> slackbox:~/tmp$ dd if=/dev/cd1 of=foo.dvd bs=2048
> ^C10270+0 records in
> 10270+0 records out
> 21032960 bytes transferred in 5.096854 secs (4126655 bytes/sec)
>
> Roland
>   
Roland is right, the blocksize is 2048 bytes.
In fact the following page is a very nice read:

http://www.troubleshooters.com/linux/coasterless.htm

The dd command would do a much more accurate image if you also specify
the length. The process is described in the page above.