异常笔记：运行hdfs copyFromLocal 上传文件报错

把本地文件系统，复制到dfs文件系统时报错的错

[hadoop@localhost ~]$ hdfs dfs -copyFromLocal /home/hadoop/mk.txt /xg_test/
03:59:35,556 WARN hdfs.DataStreamer: DataStreamer Exception
org.apache.hadoop.ipc.RemoteException(java.io.IOException): File /xg_test/mk.txt._COPYING_ could only be written to 0 of the 1 minReplication nodes. There are 0 datanode(s) running and no node(s) are excluded in this operation.
at org.apache.hadoop.hdfs.server.blockmanagement.BlockManager.chooseTarget4NewBlock(BlockManager.java:2116)
at org.apache.hadoop.hdfs.server.namenode.FSDirWriteFileOp.chooseTargetForNewBlock(FSDirWriteFileOp.java:287)
at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.getAdditionalBlock(FSNamesystem.java:2688)
at org.apache.hadoop.hdfs.server.namenode.NameNodeRpcServer.addBlock(NameNodeRpcServer.java:875)
at org.apache.hadoop.hdfs.protocolPB.ClientNamenodeProtocolServerSideTranslatorPB.addBlock(ClientNamenodeProtocolServerSideTranslatorPB.java:559)
at org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos$ClientNamenodeProtocol$2.callBlockingMethod(ClientNamenodeProtocolProtos.java)
at org.apache.hadoop.ipc.ProtobufRpcEngine$Server$ProtoBufRpcInvoker.call(ProtobufRpcEngine.java:523)
at org.apache.hadoop.ipc.RPC$Server.call(RPC.java:991)
at org.apache.hadoop.ipc.Server$RpcCall.run(Server.java:869)
at org.apache.hadoop.ipc.Server$RpcCall.run(Server.java:815)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:422)
at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1682)
at org.apache.hadoop.ipc.Server$Handler.run(Server.java:2675)

at org.apache.hadoop.ipc.Client.getRpcResponse(Client.java:1491)
at org.apache.hadoop.ipc.Client.call(Client.java:1437)
at org.apache.hadoop.ipc.Client.call(Client.java:1347)
at org.apache.hadoop.ipc.ProtobufRpcEngine$Invoker.invoke(ProtobufRpcEngine.java:228)
at org.apache.hadoop.ipc.ProtobufRpcEngine$Invoker.invoke(ProtobufRpcEngine.java:116)
at com.sun.proxy.$Proxy11.addBlock(Unknown Source)
at org.apache.hadoop.hdfs.protocolPB.ClientNamenodeProtocolTranslatorPB.addBlock(ClientNamenodeProtocolTranslatorPB.java:504)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.apache.hadoop.io.retry.RetryInvocationHandler.invokeMethod(RetryInvocationHandler.java:422)
at org.apache.hadoop.io.retry.RetryInvocationHandler$Call.invokeMethod(RetryInvocationHandler.java:165)
at org.apache.hadoop.io.retry.RetryInvocationHandler$Call.invoke(RetryInvocationHandler.java:157)
at org.apache.hadoop.io.retry.RetryInvocationHandler$Call.invokeOnce(RetryInvocationHandler.java:95)
at org.apache.hadoop.io.retry.RetryInvocationHandler.invoke(RetryInvocationHandler.java:359)
at com.sun.proxy.$Proxy12.addBlock(Unknown Source)
at org.apache.hadoop.hdfs.DFSOutputStream.addBlock(DFSOutputStream.java:1078)
at org.apache.hadoop.hdfs.DataStreamer.locateFollowingBlock(DataStreamer.java:1865)
at org.apache.hadoop.hdfs.DataStreamer.nextBlockOutputStream(DataStreamer.java:1668)
at org.apache.hadoop.hdfs.DataStreamer.run(DataStreamer.java:716)
copyFromLocal: File /xg_test/mk.txt._COPYING_ could only be written to 0 of the 1 minReplication nodes. There are 0 datanode(s) running and no node(s) are excluded in this operation.

这边出现上述问题格式化多次hadoop，导致datanode不正确，决解的办法是：

1、在hadoop数据目录下（安装目录或者自己配置的目录，根据实际情况而定）……/data/dfs/data，把里面的current文件夹删除

2、然后从新执行一下 hadoop namenode -format

3、再使用start-dfs.sh和start-yarn.sh 重启一下hadoop，用jps命令看一下就可以看见datanode启动成功后就可以了