What color is your smoke?
Blue/white/etc... this depends on what types of wood you are using. Each wood has its own color, smell and flavor of smoke it produces. It also depends on the amount of wood, and it depends on the air flow. Plus, it also depends on the temperature you're at. :) Is that enough variables?
If you have a lot of airflow, you'll be burning more fuel and typically having a whiter smoke. If you are running it kind of hot, you certainly would have some white smoke. These are not bad things; depends what you are trying to do. My smokers do both white and blue smoke depending on how I configure them and what I'm burning.
But not all white smoke is good. :) The smoke from hardwood lump coals smoldering is nasty. I haven't heard feedback on how to use them for smoking, but I suspect that you have to burn them to the point of getting white before putting them into the smoker. However that makes things difficult in a UDS.
Personally I prefer to have mine just barely ooze out the smoke, while having enough air flow to maintain that for a whole day. I have done it many times where I leave it overnight and wake up in the morning to my temp gauge reading: 225 :) The amount of air flow is not just based on size of holes but positioning and configuration of the intakes and exhaust. The typical 2inch bung hole produces a great draft, but you'll burn a bit more fuel and have a whiter smoke. If you have eight 2inch holes drilled in the lid, that is still the same circular area as a single 2inch hole, but the air flow is not shooting straight out. This causes for less fuel burn, not as white of a smoke, less smoke coming out, and possibly more moisture inside the cooker. I also have configurations where I have pipes coming out the sides of the barrel near the top. This works out well too. Always trying to keep in range of the circular area equal to the 2inch hole.
All this is from my experience in using the smokers I have for the past year and a half. I'm sure someone will come back with "mine is not doing that".