HADOOP-8247 introduces a configure flag to prevent potential status inconsistency between zkfc and namenode, by making auto and manual failover mutually exclusive.
However, as described in 2.7.2 section of design doc at
HDFS-2185, we should allow manual and auto failover co-exist, by:
- adding some rpc interfaces at zkfc
- manual failover shall be triggered by haadmin, and handled by zkfc if auto failover is enabled.