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

[Samuel Merritt <spam@andMAPScheese.org>]

On Wed, Mar 05, 2003 at 11:47:31AM -0500, Mike Simons wrote:
> 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.
> 

There is a third option; if your drive supports buffer-underrun
protection, cdrecord can use it, but does not do so by default. Use
"driveropts=burnfree" as a parameter to cdrecord to enable the
protection. 

[stuff on setting as SUID removed] 

-- 
Samuel Merritt
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