8.1 Producer8.1.1 Producing messages8.1.2 Production process for messages8.1.3 Producer and ACKs8.2 Broker8.2.1 Receiving and persisting messages8.2.2 Brokers and ACKs8.3 Data and file structures8.3.1 Metadata, checkpoints, and topics8.3.2 Partitions directory8.3.3 Log data and indices8.3.4 Segments8.3.5 Deleted topics8.4 Replication8.4.1 In-sync replicas8.4.2 High Watermark8.4.3 Effects of delays during replication