HDFS 异常，HDFS

HDFS 异常，HDFS

HDFS 异常

HTTP ERROR 500
Problem accessing /nn_browsedfscontent.jsp. Reason: 

    Cannot issue delegation token. Name node is in safe mode.
The reported blocks 0 needs additional 10 blocks to reach the threshold 0.9990 of total blocks 10.
Safe mode will be turned off automatically

Caused by:
org.apache.hadoop.hdfs.server.namenode.SafeModeException: Cannot issue delegation token. Name node is in safe mode.

重启30秒内NN处于安全模式

执行此命令即可：

hadoop dfsadmin -safemode leave