zlacker

>>pul+(OP)
> Vertical scaling — a bigger, exponentially more expensive server

This is in practice not true at all. Vertical scaling is typically a sublinear cost increase (up to a point, but that point is a ridiculous beast of a machine), since you're (typically) upgrading just the CPU and/or just the RAM or just the storage; not all of them at once.

There are instances where you can get nearly 10x the machine for 2x the cost.

>>margin+lu
The kind of server you'd run Kafka on tends to already be pretty far up the curve. I don't think I can get 10x our default broker for 20x the cost. Maybe 100x the cost. (I could probably get 2x it for 2x the cost but once you value HA the practical inflection point starts below the actual cost intersection.)