namenode

常见例句

The Datanodes also perform block creation, deletion, and replication upon instruction from the Namenode.
数据节点执行来自于名字节点的建立、删除、复制指令.
dfs.secondary.http.address ：The secondary namenode http server address and port.
如果port为0，则端口就会使用随机的可用port。
1.Replication of data blocks does not occur when the NameNode is in the Safemode state.
并不是全部检测完才退出安全模式，而是达到一个配置的比例的时候。