> I am not knowledgeable about that but I would presume there would be inertia like effects, delays. Bringing lots of servers up simultaneously may choke a cont

> I am not knowledgeable about that but I would presume there would be inertia like effects, delays. Bringing lots of servers up simultaneously may choke a contended shared resource leading to damping. In such cases one cant boot up too many servers too fast. Jerks might be better tolerated, except perhaps in high frequency trading scenario. Sure, you can model it like that. But I can actually go measure all the physical properties of the car and calculate a tuning that will work for cruise control, because the car follows known physical laws (within the limits of my ability to measure things). I can't "weigh" the datacenter. I must to some extent observe the system and empirically derive tuning. That tuning is basically overfitting PID to second and higher order effects in the system without taking the time to actually understand the root of them. Can that work? Sure. That doesn't change the fact that, IMHO, there is almost always a better way. This is probably more contraversial... but personally, I'd rather have a hacky ad hoc approach than overfit PID, because the former is so much easier to debug and understand.