如何确定哪台机器上作为secondnamenode?
hdfs-site.xml上命名配置的是2号机，莫名其妙的变成了1号机
使用hdfs创建目录遇到如下问题：
mkdir: Call From hadoop01/192.168.1.30 to hadoop01:9601 failed on connection exception: java.net.ConnectException: Connection refused; For more details see: http://wiki.apache.org/hadoop/ConnectionRefused
如何确定本机的dfs和yarn是启动状态的？