Datanode守护程序未在Hadoop 2.5.0上运行
我在一台机器上设置Hadoop 2.5.0，我遇到的问题是没有运行的datanode，如jps命令的输出所示：
$ jps 3404 Jps 2661 NodeManager 2606 ResourceManager 2484 NameNode 当我尝试手动运行它时我得到了这个：
$HADOOP_HOME/sbin/hadoop-daemon.sh start datanode starting datanode, logging to /home/arbi/Programs/hadoop-2.5.0/logs/hadoop-arbi-datanode-ElOued.out
然后仍然没有，这里是hadoop-arbi-datanode-ElOued.out ：
ulimit -a for user arbi core file size (blocks, -c) 0 data seg size (kbytes, -d) unlimited scheduling priority (-e) 0 file size (blocks, -f) unlimited pending signals (-i) 15862 max locked memory (kbytes, -l) 64 max memory size (kbytes, -m) unlimited open files (-n) 1024 pipe size (512 bytes, -p) 8 POSIX message queues (bytes, -q) 819200 real-time priority (-r) 0 stack size (kbytes, -s) 8192 cpu time (seconds, -t) unlimited max user processes (-u) 15862 virtual memory (kbytes, -v) unlimited file locks (-x) unlimited
另外在http://oued.souf.dz:50070/dfshealth.html#tab-datanode中没有可以看到的datanode。
当我提交hadoop作业时，我看到以下exception：
14/08/26 17:41:59 WARN mapreduce.JobSubmitter: Hadoop command-line option parsing not performed. Implement the Tool interface and execute your application with ToolRunner to remedy this. 14/08/26 17:41:59 WARN hdfs.DFSClient: DataStreamer Exception org.apache.hadoop.ipc.RemoteException(java.io.IOException): File /tmp/hadoop-yarn/staging/arbi/.staging/job_1409065677616_0001/job.jar could only be replicated to 0 nodes instead of minReplication (=1). There are 0 datanode(s) running and no node(s) are excluded in this operation. at org.apache.hadoop.hdfs.server.blockmanagement.BlockManager.chooseTarget(BlockManager.java:1471) at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.getAdditionalBlock(FSNamesystem.java:2791) at org.apache.hadoop.hdfs.server.namenode.NameNodeRpcServer.addBlock(NameNodeRpcServer.java:606) at org.apache.hadoop.hdfs.protocolPB.ClientNamenodeProtocolServerSideTranslatorPB.addBlock(ClientNamenodeProtocolServerSideTranslatorPB.java:455) at org.apache.hadoop.hdfs.protocol.proto.ClientNamenodeProtocolProtos$ClientNamenodeProtocol$2.callBlockingMethod(ClientNamenodeProtocolProtos.java) at org.apache.hadoop.ipc.ProtobufRpcEngine$Server$ProtoBufRpcInvoker.call(ProtobufRpcEngine.java:585) at org.apache.hadoop.ipc.RPC$Server.call(RPC.java:928) at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:2013) at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:2009) at java.security.AccessController.doPrivileged(Native Method) at javax.security.auth.Subject.doAs(Subject.java:415) at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1614) at org.apache.hadoop.ipc.Server$Handler.run(Server.java:2007) at org.apache.hadoop.ipc.Client.call(Client.java:1411) at org.apache.hadoop.ipc.Client.call(Client.java:1364) at org.apache.hadoop.ipc.ProtobufRpcEngine$Invoker.invoke(ProtobufRpcEngine.java:206) at com.sun.proxy.$Proxy14.addBlock(Unknown Source) at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method) at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:57) at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43) at java.lang.reflect.Method.invoke(Method.java:606) at org.apache.hadoop.io.retry.RetryInvocationHandler.invokeMethod(RetryInvocationHandler.java:187) at org.apache.hadoop.io.retry.RetryInvocationHandler.invoke(RetryInvocationHandler.java:102) at com.sun.proxy.$Proxy14.addBlock(Unknown Source) at org.apache.hadoop.hdfs.protocolPB.ClientNamenodeProtocolTranslatorPB.addBlock(ClientNamenodeProtocolTranslatorPB.java:368) at org.apache.hadoop.hdfs.DFSOutputStream$DataStreamer.locateFollowingBlock(DFSOutputStream.java:1449) at org.apache.hadoop.hdfs.DFSOutputStream$DataStreamer.nextBlockOutputStream(DFSOutputStream.java:1270) at org.apache.hadoop.hdfs.DFSOutputStream$DataStreamer.run(DFSOutputStream.java:526)
这是datanode日志文件的快照：
2014-08-27 10:45:05,136 INFO org.apache.hadoop.hdfs.server.common.Storage: Lock on /home/arbi/Programs/hadoop-2.5.0/hdfs/datanode/in_use.lock acquired by nodename 4825@ElOued 2014-08-27 10:45:05,146 FATAL org.apache.hadoop.hdfs.server.datanode.DataNode: Initialization failed for Block pool (Datanode Uuid unassigned) service to localhost/127.0.0.1:8020. Exiting. java.io.IOException: Incompatible clusterIDs in /home/arbi/Programs/hadoop-2.5.0/hdfs/datanode: namenode clusterID = CID-be9e77bc-dce9-4001-b7e8-947feea5c3ad; datanode clusterID = CID-e26b44b4-deb0-4c22-ae94-abe522c4c96c at org.apache.hadoop.hdfs.server.datanode.DataStorage.doTransition(DataStorage.java:477) at org.apache.hadoop.hdfs.server.datanode.DataStorage.recoverTransitionRead(DataStorage.java:226) at org.apache.hadoop.hdfs.server.datanode.DataStorage.recoverTransitionRead(DataStorage.java:254) at org.apache.hadoop.hdfs.server.datanode.DataNode.initStorage(DataNode.java:975) at org.apache.hadoop.hdfs.server.datanode.DataNode.initBlockPool(DataNode.java:946) at org.apache.hadoop.hdfs.server.datanode.BPOfferService.verifyAndSetNamespaceInfo(BPOfferService.java:278) at org.apache.hadoop.hdfs.server.datanode.BPServiceActor.connectToNNAndHandshake(BPServiceActor.java:220) at org.apache.hadoop.hdfs.server.datanode.BPServiceActor.run(BPServiceActor.java:812) at java.lang.Thread.run(Thread.java:744) 2014-08-27 10:45:05,158 WARN org.apache.hadoop.hdfs.server.datanode.DataNode: Ending block pool service for: Block pool (Datanode Uuid unassigned) service to localhost/127.0.0.1:8020 2014-08-27 10:45:05,168 INFO org.apache.hadoop.hdfs.server.datanode.DataNode: Removed Block pool (Datanode Uuid unassigned) 2014-08-27 10:45:07,169 WARN org.apache.hadoop.hdfs.server.datanode.DataNode: Exiting Datanode 2014-08-27 10:45:07,170 INFO org.apache.hadoop.util.ExitUtil: Exiting with status 0 2014-08-27 10:45:07,170 INFO org.apache.hadoop.hdfs.server.datanode.DataNode: SHUTDOWN_MSG: /************************************************************ SHUTDOWN_MSG: Shutting down DataNode at ElOued/192.168.2.206 ************************************************************/
我通过在终端中删除tmp中的hadoop目录解决了这个问题
sudo rm -r /tmp/hadoop-
然后格式化文件系统并立即启动NameNode和DataNode
*****@*****:/usr/local/hadoop$ jps 19013 SecondaryNameNode 18823 DataNode 19158 Jps 18701 NameNode
问题是由于数据节点的集群ID（ ../hadoop-2.5.0/hdfs/datanode/current/VERSION ）与namenode中的集群ID之间存在差异，如../hadoop-2.5.0/hdfs/namenode/current/VERSION 。 我只需要设置相同的CID，但不知道是什么导致了这种差异，可能是通过$HADOOP_HOME/bin/hdfs namenode -format多次格式化HDFS。