Detail
When does the database "decide" that rack awareness is in use? Is it when we observe multiple racks in the cluster or is it just when the rack-id value is different than 0? If it's the latter - does setting the rack-id back to 0 will turn off the feature flag used?Answer
The server will check this during boot time, it will check the config and not start if the feature is not enabled. Even if we try to set it dynamically once the server is up, the info command then errors out with warning.Nov 03 2023 10:48:09 GMT: WARNING (info): (cfg_info.c:1742) {test} feature key does not allow rack-aware
So, we check for a non-zero value for rack-id config. If we set the rack-id back to zero, then the rack is basically disabled.