Hello, I wrote a KIP about MirrorMaker2 Exactly-once Semantics (EOS)
https://cwiki.apache.org/confluence/display/KAFKA/KIP-656%3A+MirrorMaker2+Exactly-once+Semantics
At the high-level, it resembles the idea of how HDFS Sink Connector achieves
EOS across clusters by managing and storing the consumer offsets in an external
persistent storage, but also leverages the current Kafka EOS guarantee within a
single cluster. I have done some experiments especially for the failure cases
and I am very appreciated for comments and feedback on this KIP from bigger
audience.
