title: HDFS: Canary test failed
body: <p>Just installed HDFS using Cloudera Manager. I can access the ameNode WebUI, all nodes are alive. but I get all sorts of </p>
  
  <p><strong>Canary test failed to create file in directory /tmp/.cloudera_health_monitoring_canary_files.</strong></p>
  
  <p>I tried:</p>
  
  <p>1) <code>hadoop dfsadmin -safemode get</code>: it can be confirmed that the namenode is NOT in safe mode. Therefore there should not be any restrict to write operation.</p>
  
  <p>2) <code>hadoop fs -ls /</code>: it shows that the <code>/tmp</code> directory has full permission 777, which means anyone is supposed to put data into this directory. </p>
  
  <p>By the way, I cannot find anything special in the namenode logs. Why the canary test cannot create file in /tmp???</p>