> I assumed that hardware / software does > automaticly set the speed to a reasonable value.
And you assumed correctly. If media is *properly* supported by firmware you have *all* rights to expect that firmware automatically picks reasonable speed for it. > And now after playing around a long time I figured out > that the media is designed for 1x ;-) And formally you have all rights to expect that you firmware recognizes it as 1x media. As growisofs manual page implies -speed=1 is everything you need. > Nevertheless, I tried the version 5.13 as you recommended > but I can't switch to speed=1 (error message, that growisofs > can not switch to this speed). > When I use 5.14 and speed=1 it burns with 2x. Failure to set or pick expected speed means poor media support by firmware [or simply broken firmware]. > What can I do? Test several media brands and stick to one which works with your unit. A.