Handling partially written hint files hint file 部分写成功，

Handling partially written hint files hint file 部分写成功，

Hinted Hand off persistence是Cassandra 3才引入的功能; 

https://www.datastax.com/dev/blog/whats-coming-to-cassandra-in-3-0-improved-hint-storage-and-delivery

http://docs.datastax.com/en/cassandra/3.0/cassandra/operations/opsRepairNodesHintedHandoff.html

http://docs.datastax.com/en/cassandra/3.0/cassandra/operations/opsRepairNodesHintedHandoff.html

http://docs.datastax.com/en/cassandra/2.1/cassandra/dml/dml_about_hh_c.html

Hinted Hand Off存在哪? 存在coordinator上，因为所有的node都有可能会作为coordinator, 所以所有的node上都有可能会有hinted hand off file;

那么多长时间会flush hinted hand off到disk呢? max_hint_window_in_ms