CopyFromLocal exception DataNode cannot be started, datanode cannot be started

CopyFromLocal exception DataNode cannot be started, datanode cannot be started

CopyFromLocal: File/user/apple/test.txt. _ COPYING _ cocould only be replicated to 0 nodes instead of minReplication (= 1 ). there are 0 datanode (s) running and no node (s) are excluded in this operation.

This exception was reported when the hdfs dfs-copyFromLocal command was just executed. it was known that the datanode thread was not started only after the jps command was run. It is useless to restart, nor can you reformat namenode. It turns out that you need to delete the dfs/data folder in the root directory of hdfs and then format the namenode again.