Hadoop多次格式化出现17/12/19 00:19:51 WARN hdfs.DataStreamer: DataStreamer Excep

####在进行Hadoop伪分布式安装的时候我格式化一次，后来又修改了core-site.xml，又进行了一次格式化，然后使用MapReduce 进行测试计算的时候抛出下面的异常：

[[email protected] hadoop]$ bin/hadoop jar ./share/hadoop/mapreduce/hadoop-mapreduce-examples-2.8.1.jar pi 5 10
Number of Maps  = 5
Samples per Map = 10
17/12/19 00:19:51 WARN hdfs.DataStreamer: DataStreamer Exception
org.apache.hadoop.ipc.RemoteException(java.io.IOException): File /user/hadoop/QuasiMonteCarlo_1513613989668_1586732403/in/part0 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.
        at org.apache.hadoop.hdfs.server.blockmanagement.BlockManager.chooseTarget4NewBlock(BlockManager.java:1738)
        at org.apache.hadoop.hdfs.server.namenode.FSDirWriteFileOp.chooseTargetForNewBlock(FSDirWriteFileOp.java:265)
        at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.getAdditionalBlock(FSNamesystem.java:2496)
        at org.apache.hadoop.hdfs.server.namenode.NameNodeRpcServer.addBlock(NameNodeRpcServer.java:828)
        at org.apache.hadoop.hdfs.protocolPB.ClientNamenodeProtocolServerSideTranslatorPB.addBlock(ClientNamenodeProtocolServerSideTranslatorPB.java:506)
        at org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos$ClientNamenodeProtocol$2.callBlockingMethod(ClientNamenodeProtocolProtos.java)
        at org.apache.hadoop.ipc.ProtobufRpcEngine$Server$ProtoBufRpcInvoker.call(ProtobufRpcEngine.java:447)
        at org.apache.hadoop.ipc.RPC$Server.call(RPC.java:989)
        at org.apache.hadoop.ipc.Server$RpcCall.run(Server.java:845)
        at org.apache.hadoop.ipc.Server$RpcCall.run(Server.java:788)
        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:1807)
        at org.apache.hadoop.ipc.Server$Handler.run(Server.java:2455)

        at org.apache.hadoop.ipc.Client.getRpcResponse(Client.java:1481)
        at org.apache.hadoop.ipc.Client.call(Client.java:1427)
        at org.apache.hadoop.ipc.Client.call(Client.java:1337)
        at org.apache.hadoop.ipc.ProtobufRpcEngine$Invoker.invoke(ProtobufRpcEngine.java:227)
        at org.apache.hadoop.ipc.ProtobufRpcEngine$Invoker.invoke(ProtobufRpcEngine.java:116)
        at com.sun.proxy.$Proxy10.addBlock(Unknown Source)
        at org.apache.hadoop.hdfs.protocolPB.ClientNamenodeProtocolTranslatorPB.addBlock(ClientNamenodeProtocolTranslatorPB.java:440)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:497)
        at org.apache.hadoop.io.retry.RetryInvocationHandler.invokeMethod(RetryInvocationHandler.java:398)
        at org.apache.hadoop.io.retry.RetryInvocationHandler$Call.invokeMethod(RetryInvocationHandler.java:163)
        at org.apache.hadoop.io.retry.RetryInvocationHandler$Call.invoke(RetryInvocationHandler.java:155)
        at org.apache.hadoop.io.retry.RetryInvocationHandler$Call.invokeOnce(RetryInvocationHandler.java:95)
        at org.apache.hadoop.io.retry.RetryInvocationHandler.invoke(RetryInvocationHandler.java:335)
        at com.sun.proxy.$Proxy11.addBlock(Unknown Source)
        at org.apache.hadoop.hdfs.DataStreamer.locateFollowingBlock(DataStreamer.java:1733)
        at org.apache.hadoop.hdfs.DataStreamer.nextBlockOutputStream(DataStreamer.java:1536)
        at org.apache.hadoop.hdfs.DataStreamer.run(DataStreamer.java:658)
org.apache.hadoop.ipc.RemoteException(java.io.IOException): File /user/hadoop/QuasiMonteCarlo_1513613989668_1586732403/in/part0 could only be replicated to 0 nodes instead of minReplication (=1).  There are 0 datanode(s) running and no node(s) are excluded in this operation.
        at org.apache.hadoop.hdfs.server.blockmanagement.BlockManager.chooseTarget4NewBlock(BlockManager.java:1738)
        at org.apache.hadoop.hdfs.server.namenode.FSDirWriteFileOp.chooseTargetForNewBlock(FSDirWriteFileOp.java:265)
        at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.getAdditionalBlock(FSNamesystem.java:2496)
        at org.apache.hadoop.hdfs.server.namenode.NameNodeRpcServer.addBlock(NameNodeRpcServer.java:828)
        at org.apache.hadoop.hdfs.protocolPB.ClientNamenodeProtocolServerSideTranslatorPB.addBlock(ClientNamenodeProtocolServerSideTranslatorPB.java:506)
        at org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos$ClientNamenodeProtocol$2.callBlockingMethod(ClientNamenodeProtocolProtos.java)
        at org.apache.hadoop.ipc.ProtobufRpcEngine$Server$ProtoBufRpcInvoker.call(ProtobufRpcEngine.java:447)
        at org.apache.hadoop.ipc.RPC$Server.call(RPC.java:989)
        at org.apache.hadoop.ipc.Server$RpcCall.run(Server.java:845)
        at org.apache.hadoop.ipc.Server$RpcCall.run(Server.java:788)
        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:1807)
        at org.apache.hadoop.ipc.Server$Handler.run(Server.java:2455)

        at org.apache.hadoop.ipc.Client.getRpcResponse(Client.java:1481)
        at org.apache.hadoop.ipc.Client.call(Client.java:1427)
        at org.apache.hadoop.ipc.Client.call(Client.java:1337)
        at org.apache.hadoop.ipc.ProtobufRpcEngine$Invoker.invoke(ProtobufRpcEngine.java:227)
        at org.apache.hadoop.ipc.ProtobufRpcEngine$Invoker.invoke(ProtobufRpcEngine.java:116)
        at com.sun.proxy.$Proxy10.addBlock(Unknown Source)
        at org.apache.hadoop.hdfs.protocolPB.ClientNamenodeProtocolTranslatorPB.addBlock(ClientNamenodeProtocolTranslatorPB.java:440)
        at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
        at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
        at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
        at java.lang.reflect.Method.invoke(Method.java:497)
        at org.apache.hadoop.io.retry.RetryInvocationHandler.invokeMethod(RetryInvocationHandler.java:398)
        at org.apache.hadoop.io.retry.RetryInvocationHandler$Call.invokeMethod(RetryInvocationHandler.java:163)
        at org.apache.hadoop.io.retry.RetryInvocationHandler$Call.invoke(RetryInvocationHandler.java:155)
        at org.apache.hadoop.io.retry.RetryInvocationHandler$Call.invokeOnce(RetryInvocationHandler.java:95)
        at org.apache.hadoop.io.retry.RetryInvocationHandler.invoke(RetryInvocationHandler.java:335)
        at com.sun.proxy.$Proxy11.addBlock(Unknown Source)
        at org.apache.hadoop.hdfs.DataStreamer.locateFollowingBlock(DataStreamer.java:1733)
        at org.apache.hadoop.hdfs.DataStreamer.nextBlockOutputStream(DataStreamer.java:1536)
        at org.apache.hadoop.hdfs.DataStreamer.run(DataStreamer.java:658)
           

错误原因：由于进行了多次格式化使得datanode无法正常启动，即出现

下面的错误信息：

17/12/19 00:19:51 WARN hdfs.DataStreamer: DataStreamer Exception
org.apache.hadoop.ipc.RemoteException(java.io.IOException): File /user/hadoop/QuasiMonteCarlo_1513613989668_1586732403/in/part0 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.
           

百度上总结了很多基本解决办法，总结如下:

• 先后启动namenode、datanode

$hadoop-daemon.sh start namenode
$hadoop-daemon.sh start datanode
           

• 确保master（namenode） 、slaves（datanode）的防火墙已经关闭
• 确保DFS空间的使用情况
• Hadoop默认的hadoop.tmp.dir的路径为/tmp/hadoop-${user.name},而有的linux系统的/tmp目录文件系统的类型往往是Hadoop不支持的。

但还是不行，原因是因为当我们执行文件系统格式化时，会在namenode数据文件夹（/tmp/hadoop-hadoop/dfs/data/current）中保存一个current/VERSION文件，记录namespaceID，标识了所格式化的 namenode的版本。如果我们频繁的格式化namenode，那么datanode中保存（即配置文件中dfs.data.dir在本地系统的路径）的current/VERSION文件只是你第一次格式化时保存的namenode的ID，因此就会造成datanode与namenode之间的id不一致。

####以下提供两种解决办法：

#####方式1

• 删除前先关闭进程

[[email protected] sbin]$ jps
26884 Jps
26043 SecondaryNameNode
25756 NameNode
[[email protected] sbin]$ kill -9 26043
[[email protected] sbin]$ kill -9 25756
           

• 删除

  /tmp/hadoop-hadoop/dfs/data/

  data目录下的文件

[[email protected] ~]$ cd /tmp/hadoop-hadoop/dfs/data/
[[email protected] data]$ ll
total 8
drwxrwxr-x. 3 hadoop hadoop 4096 Dec 19 00:33 current
-rw-rw-r--. 1 hadoop hadoop   21 Dec 19 00:33 in_use.lock
[[email protected] data]$ rm -rf current
           

• 这时候在进行格式化

  [[email protected] bin]$ hdfs namenode -format

问题就解决了。

#####方式2

• 修改current目录的VERSION中的clusterID使两个的clusterID相同，就可以解决了（/tmp/hadoop-hadoop/dfs/data/）

[[email protected] ~]$ cd /tmp/hadoop-hadoop/dfs/data/
[[email protected] data]$ ll
total 8
drwxrwxr-x. 3 hadoop hadoop 4096 Dec 19 00:33 current
-rw-rw-r--. 1 hadoop hadoop   21 Dec 19 00:33 in_use.lock

[[email protected] current]$ cat VERSION 
#Tue Dec 19 00:33:48 CST 2017
storageID=DS-d9b740ba-fe83-44ec-b3d2-e21da706a597
clusterID=CID-2544b3e3-8400-47a6-a253-63dffc356e47
cTime=0
datanodeUuid=79d78c7d-cd1b-4854-89df-c063ce5fba86
storageType=DATA_NODE
layoutVersion=-57
           

• 这时候在进行格式化

  [[email protected] bin]$ hdfs namenode -format

格式化之后jps查看datanode启动。问题就解决了。