1.1 Introduction中 Guarantees官网剖析（博主推荐）

　不多说，直接上干货！

　　一切来源于官网

http://kafka.apache.org/documentation/

Guarantees

Kafka的保证(Guarantees)

At a high-level Kafka gives the following guarantees:

• Messages sent by a producer to a particular topic partition will be appended in the order they are sent. That is, if a record M1 is sent by the same producer as a record M2, and M1 is sent first, then M1 will have a lower offset than M2 and appear earlier in the log.
• A consumer instance sees records in the order they are stored in the log.
• For a topic with replication factor N, we will tolerate up to N-1 server failures without losing any records committed to the log.

1、生产者发送到一个特定的Topic的分区上，消息将会按照它们发送的顺序依次加入，也就是说，如果一个消息M1和M2使用相同的producer发送，M1先发送，那么M1将比M2的offset低，并且优先的出现在日志中。
2、消费者收到的消息也是此顺序。
3、如果一个Topic配置了复制因子（replication facto）为N， 那么可以允许N-1服务器宕机而不丢失任何已经提交（committed）的消息。

More details on these guarantees are given in the design section of the documentation.

有关这些保证的更多详细信息，请参见文档的设计部分。