hadoop非正常关闭启动了安全模式：
查看hadoop安全模式状态： hadoop dfsadmin -safemode get
结果：
[root@hadoop102 ~]# hadoop dfsadmin -safemode get
WARNING: Use of this script to execute dfsadmin is deprecated.
WARNING: Attempting to execute replacement "hdfs dfsadmin" instead.
Safe mode is ON
关闭hadoop安全模式： hadoop dfsadmin -safemode forceExit
结果：
[root@hadoop102 ~]# hadoop dfsadmin -safemode forceExit
WARNING: Use of this script to execute dfsadmin is deprecated.
WARNING: Attempting to execute replacement "hdfs dfsadmin" instead.
Safe mode is OFF
