[Linux][Hadoop] 将hadoop跑起来，linuxhadoop跑起来


前面安装过程待补充，安装完成hadoop安装之后，开始执行相关命令，让hadoop跑起来

 

使用命令启动所有服务：

hadoop@ubuntu:/usr/local/gz/hadoop-2.4.1$ ./sbin/start-all.sh

当然在目录hadoop-2.4.1/sbin下面会有很多启动文件：

#!/usr/bin/env bash # Licensed to the Apache Software Foundation (ASF) under one or more # contributor license agreements. See the NOTICE file distributed with # this work for additional information regarding copyright ownership. # The ASF licenses this file to You under the Apache License, Version 2.0 # (the "License"); you may not use this file except in compliance with # the License. You may obtain a copy of the License at # # http://www.apache.org/licenses/LICENSE-2.0 # # Unless required by applicable law or agreed to in writing, software # distributed under the License is distributed on an "AS IS" BASIS, # WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. # See the License for the specific language governing permissions and # limitations under the License. # Start all hadoop daemons. Run this on master node. echo "This script is Deprecated. Instead use start-dfs.sh and start-yarn.sh" #这里说明了这个脚本已经被弃用了，要我们使用start-dfs.sh和start-yarn.sh来进行启动 


bin=`dirname "${BASH_SOURCE-$0}"`
bin=`cd "$bin"; pwd`

DEFAULT_LIBEXEC_DIR="$bin"/../libexec
HADOOP_LIBEXEC_DIR=${HADOOP_LIBEXEC_DIR:-$DEFAULT_LIBEXEC_DIR}
. $HADOOP_LIBEXEC_DIR/hadoop-config.sh  #这里执行相关配置文件在hadoop/libexec/hadoop-config.sh，该配置文件里面全是配置相关路径的，CLASSPATH, export相关的

#真正执行的是以下两个，也就是分别执行start-dfs.sh和start-yarn.sh两个脚本，以后还是自己分别执行这两个命令
# start hdfs daemons if hdfs is present
if [ -f "${HADOOP_HDFS_HOME}"/sbin/start-dfs.sh ]; then
  "${HADOOP_HDFS_HOME}"/sbin/start-dfs.sh --config $HADOOP_CONF_DIR
fi

# start yarn daemons if yarn is present
if [ -f "${HADOOP_YARN_HOME}"/sbin/start-yarn.sh ]; then
  "${HADOOP_YARN_HOME}"/sbin/start-yarn.sh --config $HADOOP_CONF_DIR
fi

执行完成之后调用jps查看是否所有服务都已经启动起来了：

2014-07-21 22:05:21,064 INFO org.apache.hadoop.hdfs.server.common.Storage: Lock on /usr/local/gz/hadoop-2.4.1/dfs/data/in_use.lock acquired by nodename 3312@ubuntu 2014-07-21 22:05:21,075 FATAL org.apache.hadoop.hdfs.server.datanode.DataNode: Initialization failed for Block pool <registering> (Datanode Uuid unassigned) service to localhost/127.0.0.1:9000. Exiting. java.io.IOException: Incompatible clusterIDs in /usr/local/gz/hadoop-2.4.1/dfs/data: namenode clusterID = CID-2cfdb22e-07b2-4ab8-965d-fdb27645bd62; datanode clusterID = ID-2cfdb22e-07b2-4ab8-965d-fdb27645bd62 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:974) at org.apache.hadoop.hdfs.server.datanode.DataNode.initBlockPool(DataNode.java:945) 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:816) at java.lang.Thread.run(Thread.java:722) 2014-07-21 22:05:21,084 WARN org.apache.hadoop.hdfs.server.datanode.DataNode: Ending block pool service for: Block pool <registering> (Datanode Uuid unassigned) service to localhost/127.0.0.1:9000 2014-07-21 22:05:21,102 INFO org.apache.hadoop.hdfs.server.datanode.DataNode: Removed Block pool <registering> (Datanode Uuid unassigned) 2014-07-21 22:05:23,103 WARN org.apache.hadoop.hdfs.server.datanode.DataNode: Exiting Datanode 2014-07-21 22:05:23,106 INFO org.apache.hadoop.util.ExitUtil: Exiting with status 0 2014-07-21 22:05:23,112 INFO org.apache.hadoop.hdfs.server.datanode.DataNode: SHUTDOWN_MSG: /************************************************************ SHUTDOWN_MSG: Shutting down DataNode at ubuntu/127.0.1.1 ************************************************************/ 

根据错误日志搜索之后发现是由于先前启动Hadoop之后，再使用命令格式化namenode会导致，datanode和namenode的clusterID不一致：
找到hadoop/etc/hadoop/hdfs-site.xml配置文件里配置的datanode和namenode下的./current/VERSION，文件，对比两个文件中的clusterID，不一致，将Datanode下的clusterID改为namenode下的此ID，重新启动之后即可。
参考连接：
http://www.cnblogs.com/kinglau/p/3796274.html

学习hadoop需要先学习linux？

你学hadoop的动机是什么？只是玩玩而已么。还是想从事这方面。
如果是后者，那么不学linux那就是个笑话，hadoop，直白点来说是多个主机来做一个存储或数据库，你不学习linux怎么配置各个linux的环境？怎么控制他的负载均衡？
甚至你需要学习网络等方面的知识，里面的一些报错很抽象，需要根据一些网络基础判断出错原因。
 

linux操作系统：用hadoop架构做开发，用哪个linux操作系统比较好，了

用hadoop不在与那个linux系统好，而是hadoop最好在linux下，其实linux都差不多，内核都是一样的，用起来也都大同小异，我用的是centos，推荐cenos，现在很多公司都用centos
 

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