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The following is an archive of a post made to our 'vox-tech mailing list' by one of its subscribers.

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Re: [vox-tech] Burning CD's in Linux
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Re: [vox-tech] Burning CD's in Linux



On Tue, Mar 04, 2003 at 05:30:38PM -0800, Michael J Wenk wrote:
> the general command I use is:
> cdrecord dev=0,0,0 speed=8 -data -dao /tmp/myiso.iso
[...] 
> (my windows burner is also quite a bit faster than
> my linux one, though I don't make as many coasters with linux.)

Mike,

Two things:
- When you say the windows burner is faster, do you mean actual burn
  time or your time spent to get a burn setup?
- When you say you make coasters under Linux is that because the
  cdrecord couldn't keep up with the data needs of the drive, or 
  because you selected the wrong set of files?

... 

  If the windows software actually burns to disk faster, it seems you
should raise the "speed" option higher... to whatever your drive's rated
speed is.  If the cdrecord is told to burn at the same speed as the
windows software the burn time should be within a few seconds of each
other.

  Perhaps you lowered the burn speed because you are making coasters,
and are making toasters due to buffer underruns... there are two options
to look into to fix this:

- cdrecord uses a buffer to send things to the drive, the default size 
  4meg is the _minimum_ recommended size, it should be increased if you
  are running high speed burns... check out the "fs" option.  The man
  page talks about correct sizing of this buffer... then doing a number
  of test runs (--dummy) to verify the speed and buffer are working
  together.

- cdrecord will run as a real-time process which will prevent other
  normal CPU load from interfering with a data burn (*).  However,
  in order to raise the scheduling mode from normal to real-time
  the cdrecord process must be running as root.  If you normally run 
  burns as a user you should try having cdrecord run as root even when
  normal users run it... with chmod and such (example below).

*: massive amounts of disk activity could still interfere with retrieving
  the data from disk enough to cause buffer underruns.


To SUID root the cdrecord command:

  Add the following line to 

/etc/groups
===
cdrw:x:USER1,USER2,USER3
===

  You will need to log out and log back in as whichever user you want to
do the burning, for the change to /etc/group to take effect.


Run the following commands as root:
===
chown root `which cdrecord`
chgrp cdrw `which cdrecord`
chmod 4710 `which cdrecord`
===

    Later,
      Mike Simons




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