伪分布模式：
Hadoop可以在单节点上以伪分布模式运行，用不同的Java进程模拟分布式运行中的各类节点。
1、安装Hadoop
确保系统已安装好JDK和ssh。
1）在官网下载Hadoop： 我这里下载的是 hadoop-1.1.1-bin.tar.gz
2）下载后放到/softs目录下
3）将hadoop-1.1.1-bin.tar.gz解压到/usr目录
[root@localhost usr]# tar -zxvf /softs/hadoop-1.1.1-bin.tar.gz
[root@localhost usr]# lsbin etc games hadoop-1.1.1 include java lib libexec local lost+found sbin share src tmp[root@localhost usr]#
2、配置Hadoop
1）配置/usr/hadoop-1.1.1/conf/hadoop-env.sh文件，找到export JAVA_HOME，修改为JDK的安装路径
export JAVA_HOME=/usr/java/jdk1.6.0_38
2）配置/usr/hadoop-1.1.1/conf/core-site.xml，内容如下：
fs.default.namehdfs://localhost:9000
3）配置/usr/hadoop-1.1.1/conf/hdfs-site.xml，内容如下：
dfs.replication1
4）配置/usr/hadoop-1.1.1/conf/mapred-site.xml，虚拟主机，内容如下：
mapred.job.trackerlocalhost:9001
3、免密码SSH设置
Hadoop运行过程中需要使用ssh管理远端Hadoop守护进程，需要不用输入密码就可以访问，美国空间，所以这里设置用密钥验证。
1）生成密钥，执行如下命令：
[root@localhost ~]# ssh-keygen -t rsa
提示输入Enter passphrase (empty for no passphrase): 和 Enter same passphrase again:时，无需输入任何东西，虚拟主机，直接按回车键即可。
[root@localhost ~]# ssh-keygen -t rsaGenerating public/private rsa key pair.Enter file in which to save the key (/root/.ssh/id_rsa): Created directory ‘/root/.ssh’.Enter passphrase (empty for no passphrase): Enter same passphrase again: Your identification has been saved in /root/.ssh/id_rsa.Your public key has been saved in /root/.ssh/id_rsa.pub.The key fingerprint is:16:54:ed:23:0c:04:fa:74:1b:b0:b5:eb:c3:87:43:52 root@localhost.localdomainThe key’s randomart image is:+–[ RSA 2048]—-+|oo+…||. =.. . || . o Eo .||o o =o o ||o S . . ||* .||* .||+|||+—————–+[root@localhost ~]# ls
从上面执行的结果可以看到，生成的密钥已经保存到/root/.ssh/id_rsa中。
2）进入到/root/.ssh目录，执行如下命令
[root@localhost .ssh]# cp id_rsa.pub authorized_keys
3）接着执行：
[root@localhost .ssh]# ssh localhost
可以实现无需输入密码就可以用ssh连接
[root@localhost .ssh]# ssh localhostThe authenticity of host ‘localhost (::1)’ can’t be established.RSA key fingerprint is e5:44:06:97:b4:66:ba:89:40:95:ba:23:0a:06:2a:74.Are you sure you want to continue connecting (yes/no)? yesWarning: Permanently added ‘localhost’ (RSA) to the list of known hosts.Last login: Tue Jan 15 22:08:06 2013 from 192.168.0.101Hello,man[root@localhost ~]#
4、运行Hadoop
1）格式化分布式文件系统：
[root@localhost hadoop-1.1.1]# bin/hadoop namenode -format
[root@localhost hadoop-1.1.1]# bin/hadoop namenode -format13/01/15 23:56:53 INFO namenode.NameNode: STARTUP_MSG: /************************************************************STARTUP_MSG: Starting NameNodeSTARTUP_MSG: host = localhost.localdomain/127.0.0.1STARTUP_MSG: args = [-format]STARTUP_MSG: version = 1.1.1STARTUP_MSG: build = https://svn.apache.org/repos/asf/hadoop/common/branches/branch-1.1 -r 1411108; compiled by ‘hortonfo’ on Mon Nov 19 10:48:11 UTC 2012************************************************************/13/01/15 23:56:54 INFO util.GSet: VM type= 32-bit13/01/15 23:56:54 INFO util.GSet: 2% max memory = 19.33375 MB13/01/15 23:56:54 INFO util.GSet: capacity= 2^22 = 4194304 entries13/01/15 23:56:54 INFO util.GSet: recommended=4194304, actual=419430413/01/15 23:56:55 INFO namenode.FSNamesystem: fsOwner=root13/01/15 23:56:55 INFO namenode.FSNamesystem: supergroup=supergroup13/01/15 23:56:55 INFO namenode.FSNamesystem: isPermissionEnabled=true13/01/15 23:56:55 INFO namenode.FSNamesystem: dfs.block.invalidate.limit=10013/01/15 23:56:55 INFO namenode.FSNamesystem: isAccessTokenEnabled=false accessKeyUpdateInterval=0 min(s), accessTokenLifetime=0 min(s)13/01/15 23:56:55 INFO namenode.NameNode: Caching file names occuring more than 10 times 13/01/15 23:56:55 INFO common.Storage: Image file of size 110 saved in 0 seconds.13/01/15 23:56:55 INFO namenode.FSEditLog: closing edit log: position=4, editlog=/tmp/hadoop-root/dfs/name/current/edits13/01/15 23:56:55 INFO namenode.FSEditLog: close success: truncate to 4, editlog=/tmp/hadoop-root/dfs/name/current/edits13/01/15 23:56:55 INFO common.Storage: Storage directory /tmp/hadoop-root/dfs/name has been successfully formatted.13/01/15 23:56:55 INFO namenode.NameNode: SHUTDOWN_MSG: /************************************************************SHUTDOWN_MSG: Shutting down NameNode at localhost.localdomain/127.0.0.1************************************************************/[root@localhost hadoop-1.1.1]#
2）启动Hadoop守护进程
[root@localhost hadoop-1.1.1]# bin/start-all.sh
辽远或偏僻的地方，而会常常想起这一次的旅行，
