一、环境准备
1、系统环境
CentOS 7
2、软件环境
- OpenJDK
# 查询可安装的OpenJDK软件包
[root@server1] yum search java | grep jdk
...
# 选择1.8.0版本安装，包括运行环境（openjdk）和开发环境（openjdk-devel）
[root@server1] yum install -y java-1.8.-openjdk.x86_64 java-1.8.-openjdk-devel.x86_64
- SSH
[root@server1] yum install -y ssh
- Hadoop
在mirror.bit.edu.cn/apache/hadoop/common/上下载合适的Hadoop版本，这里选择hadoop-2.7.3.tar.gz
二、配置Hadoop
1、解压缩hadoop-2.7.3.tar.gz
2、配置JAVA_HOME
[root@server1 hadoop]# vim etc/hadoop/hadoop-env.sh
# set to the root of your Java installation
export JAVA_HOME=/usr # 这里一定要注意，是去掉/bin/java的目录
3、配置系统环境变量
[root@server1 hadoop]# vim /etc/profile
...
export HADOOP_PREFIX=/usr/local/hadoop
export PATH=$PATH:$HADOOP/bin
...
[root@server1 hadoop]# source /etc/profile
三、测试Hadoop
[root@server1 hadoop]# ./bin/hadoop
Usage: hadoop [--config confdir] [COMMAND | CLASSNAME]
CLASSNAME run the class named CLASSNAME
or
where COMMAND is one of:
fs run a generic filesystem user client
version print the version
jar <jar> run a jar file
note: please use "yarn jar" to launch
YARN applications, not this command.
checknative [-a|-h] check native hadoop and compression libraries availability
distcp <srcurl> <desturl> copy file or directories recursively
archive -archiveName NAME -p <parent path> <src>* <dest> create a hadoop archive
classpath prints the class path needed to get the
credential interact with credential providers
Hadoop jar and the required libraries
daemonlog get/set the log level for each daemon
trace view and modify Hadoop tracing settings Most commands print help when invoked w/o parameters.
四、运行Hadoop
因为这里只有一台服务器，因此采用Standalone模式运行，执行一个任务
[root@server1 hadoop]# mkdir input
[root@server1 hadoop]# cp etc/hadoop/*.xml input
[root@server1 hadoop]# bin/hadoop jar share/hadoop/mapreduce/hadoop-mapreduce-examples-2.7.3.jar grep input output 'dfs[a-z.]+'
...
16/09/01 16:05:25 INFO mapreduce.Job: Counters: 30
File System Counters
FILE: Number of bytes read=1248142
FILE: Number of bytes written=2318080
FILE: Number of read operations=0
FILE: Number of large read operations=0
FILE: Number of write operations=0
Map-Reduce Framework
Map input records=1
Map output records=1
Map output bytes=17
Map output materialized bytes=25
Input split bytes=121
Combine input records=0
Combine output records=0
Reduce input groups=1
Reduce shuffle bytes=25
Reduce input records=1
Reduce output records=1
Spilled Records=2
Shuffled Maps =1
Failed Shuffles=0
Merged Map outputs=1
GC time elapsed (ms)=24
Total committed heap usage (bytes)=262553600
Shuffle Errors
BAD_ID=0
CONNECTION=0
IO_ERROR=0
WRONG_LENGTH=0
WRONG_MAP=0
WRONG_REDUCE=0
File Input Format Counters
Bytes Read=123
File Output Format Counters
Bytes Written=23
...
[root@server1 hadoop]# cat output/*
1 dfsadmin
五、遇到的问题
1、找不到java命令
export JAVA_HOME=/usr，这个hadoop环境变量一定要设置为父目录
2、metrics.MetricsUtil: Unable to obtain hostName
[root@server1 hadoop]# vim /etc/hosts
127.0.0.1 server1