These release notes cover new developer and user-facing incompatibilities, important issues, features, and major improvements.
Support multi-thread pre-read in AliyunOSSInputStream to improve the sequential read performance from Hadoop to Aliyun OSS.
Added an option to not disables short-circuit reads on failures, by setting dfs.domain.socket.disable.interval.seconds to 0.
Fix the document error of setting up HFDS Router Federation
HDFS NameNode default RPC port is changed back to 8020. The only official release that has this differently is 3.0.0, which used 9820.
It is recommended for 2.x users to upgrade to 3.0.1+, to reduce the burden on changing default NN RPC port.