I'm highly skeptical of the method employed to simulate unsync'd writes in that example.
Using a non-clustered zookeeper and then just shutting it down, breaking the kafka controller and preventing any kafka cluster state management (not just preventing partition leader election) while manually corrupting the log file. Oof. Is it really _that_ hard to lose ack'd data from a kafka cluster that you had to go to such contrived and dubious lengths?
To be fair, since without fsync you don't have any ordering guarantees for your writes, a crash has a good chance of corrupting your data, not just losing recent writes.
