[Linux][Hadoop] 将hadoop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：

里面会有所有服务各自启动的命令，而start-all.sh则是把所有服务一起启动，以下为.sh的内容：

#!/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
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#     http://www.apache.org/licenses/LICENSE-2.0
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# distributed under the License is distributed on an "AS IS" BASIS,
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# 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：

这里注意，一定要有6个服务，我启动的时候当时只有5个服务，打开两个连接都成功http://192.168.1.107:50070/，http://192.168.1.107:8088/，但是在执行wordcount示例的时候，发现执行失败，查找原因之后，才发起我启动的时候少了datanode服务

下面这个是application的运行情况：

下面这个是dfs的健康状态：

http://192.168.1.107:50070/打开的页面可以查看hadoop启动及运行的日志，详情如下：

我就是通过这里的日志找到问题原因的，打开日志之后是各个服务运行的日志文件：

此时打开datanode-ubuntu.log文件，有相关异常抛出：

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