Hadoop问题：There are 0 datanode(s) running and no node(s) are excluded in this operation.

问题描述： org.apache.hadoop.ipc.RemoteException(java.io.IOException): File /tmp/hadoop-yarn/staging/hadoop/.staging/job_1519998981934_0001/job.jar could 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.

问题分析：There are 0 datanode(s) 使用jps查看有哪些进程正在运行，发现datanode节点没有在运行说明是由于该节点没有正常启动导致数据无法存放，从而发生错误。

问题解决：停止现在运行的所有进程，然后重新启动。主要是 datanode.