报错：
Caused by: org.apache.hadoop.ipc.RemoteException(org.apache.hadoop.hdfs.server.namenode.SafeModeException): Cannot create directory /home/data/software/hadoop-3.2.2/hadoop-data/tmp/yarn/system/rmstore/FSRMStateRoot/RMDTSecretManagerRoot. Name node is in safe mode. The reported blocks 192 has reached the threshold 0.9990 of total blocks 192. The minimum number of live datanodes is not required. In safe mode extension. Safe mode will be turned off automatically in 17 seconds. NamenodeHostName:craw-node212
当用root用户启动的时候hdfs会有安全模式:
需要先启动hdfs，关闭安全模式，在启动yarn
hadoop dfsadmin -safemode get 命令是用来查看当前hadoop安全模式的开关状态
hadoop dfsadmin -safemode enter 命令是打开安全模式
hadoop dfsadmin -safemode leave 命令是离开安全模式.
