title: Hadoop localhost:9870 don't work before format hdfs namenode
body: <p>I have installed the hadoop.</p>
  
  <p>When I start dfs and yarn, just yarn localhost work. For dfs localhost work, I need to do "bin/hdfs namenode -format" every time I start my laptop, and then start dfs, and it works.</p>
  
  <p>How can I fix this ?
  Sorry my bad english</p>