Re: Unidentified subject!

[Bill Davidsen <davidsen@tmr.com>]

Joerg Schilling wrote:

Rob Bogus <rob23@tmr.com> wrote:

  

I think size checking is done only for ISO images. If you feed from a 
source, using a non-ISO image, I believe you bypass that logic. Unlike 
cdrecord, growisofs can burn from a pipe.
    

I recommend you to read the documentation from cdrtools to learn that your  
claim is not true: cdrecord of course can burn from a pipe. 
  

To be more correct, cdrecord can not burn from a pipe with anything useful writing the pipe, while growisofs can. cdrecord requires that the total size of the data be known before starting, which means that the usual benefits of using a pipe are not possible:

• avoid having to write an image to disk when space is tight
• allow overlapping of image creation and burning time
• allow burning data which changes in size between observation

So if you can't know the exact size of the image before you start, you can't burn from a pipe. Actually, I don't think you can burn at all with dynamic data, there are old posts here indicating that even using the builtin mkisofs, if the files are growing there can be problems. The final size can be on the command line or in the ISO image, but must be known at the start of the burn. See the man page "isosize" and "tsize=" descriptions. The latter explains that cdrecord uses modes which require the information early.

Last tested on 2.01.01a30 on both 2.4 and 2.6 base Linux. Backup process writes a data stream of length 3.8 to 4.1GB, size is a multiple of 32k, growisofs writes the DVD, cdrecord writes the error message.

-- 
Bill Davidsen <davidsen@tmr.com>
  "We have more to fear from the bungling of the incompetent than from
the machinations of the wicked."  - from Slashdot