Hm...
At first I've noticed the problem when I tried to burn a DVD-image on the disk. I specified write speed with -spped=4, but in the output of the command I've seen that speed was 0.8-5.9x, and changed very fast in this range. Then I tried to check the md5 hash of the disk:
$cat /dev/dvd | head -c <size> | md5sum
and a few seconds later I got the "Input/output error" message. But I still can mount this disk and even boot from it.
Later I noticed, that writing is a bit more stable when I don't touch any other programs at all, and recording process is on the foreground. But It doesn't solve the problem completely.
I tried to renice the process to (-5) - no effect.
It seems that the -speed option is ignored - it has no effect. Maximum speed is always near 5.9-6.0 if the media allows.
Also when I record DVD-RW media with max record speed 4 (on the foreground, nothing else is running) it's relatively stable.
Can I do something to make this process more reliable?

I dont know about that "Input/Output Error" but when Im burning the speed bounces too. So maybe its just normal Not sure actually.

But I think you continue working while there is the process of recording?
And I have to stop everything, because otherwise I'll corrupt the disc

Maybe some additional information is necessary?

Oh... Sry. I dont know then. If no-one else knows maybe you could ask from your distros support.