Re: growisofs failed to change write speed

["Christopher J. Bottaro" <cjbottaro@alumni.cs.utexas.edu>]

Andy Polyakov wrote:

>>>>Please, check the version explicitly with 'growisofs -version'. I [for
>>>>one] don't keep track on which version is shipped with any particular
>>>>distro or when updated. If it's less than 5.19 (as mentioned at
>>>>http://fy.chalmers.se/~appro/linux/DVD+RW/hcn.hml), then update. If not,
>>>>submit the actual dvd+rw-mediainfo output for the media in question.
>> 
>> ok, the problem got worse when i upgraded to 5.21.  now growisofs changes
>> the write speed to 8x, but the actual writing of the disk tops out at
>> 2.5x.
> 
> Is it possible that DMA was on by then, but not now anymore? Then keep
> in mind that if you set recording velocity to value higher than your
> system can sustain, then resulting *actual* or *effective* speed doesn't
> flat out at the latter value, but on some value *lower* than that. And
> depending on firmware implementation it can apparently drop down
> *dramatically*. In other words if your system for example can manage
> only 6x [for whatever reason, which most likely will end up beyond the
> scope of this discussion] and you make unit record at 8x velocity, the
> resulting *effective* speed might as well be 2.5x. That's because unit
> will have to take idle revolutions... For optimal performance [and
> recording results] you should choose recording speed just a bit lower
> than your system can deliver. A.

Thanks for the reply, that was very helpful.  Unfortunately, I haven't had
time recently to play around with it to try to fix the problem.  I'll post
when (if) I figure it out.

Thanks.