For kafka are people using group.id. Trying to work out how the replication works e.g. say 2 replicas of a segment, is this 2 servers ingesting the same kafka messages (in which case guess setting group.id won't work) or one server ingesting from kafka and then copying the segments to another server for replication.

Two servers ingesting the same Kafka messages

what is managing the committed offsets, pinot or kafka? guess I should try removing kafka group ID from the table spec

Pinot

any easy way to check consumer lags in the controller ui?