org.apache.hadoop.ipc.RemoteException(java.io.IOException): File /user/a.txt._COPYING_ 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.
关闭hadoop群上所有节点的 firewall(防火墙)
chkconfig iptables off
service iptables stop
chkconfig iptables --list //查看防火墙开机的状态
service iptables status //查看防火墙当前的状态