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Hadoop模式介绍
单机模式：安装简单，几乎不用作任何配置，但仅限于调试用途
伪分布模式：在单节点上同时启动 namenode、datanode、jobtracker、tasktracker、secondary namenode 等5个进程，模拟分布式运行的各个节点
完全分布式模式：正常的 Hadoop 集群，由多个各司其职的节点构成
安装环境
操作平台：vmware2
操作系统：Oracle linux 5.6
软件版本：hadoop-0.22.0,jdk-6u18
集群架构：3 node，master node(gc),slave node(rac1,rac2)
安装步骤
1. 下载 Hadoop 和jdk：
http://mirror.bit.edu.cn/apache/hadoop/common/
如：hadoop-0.22.0
2. 配置 hosts 文件
所有的节点（gc,rac1,rac2）都修改/etc/hosts，使彼此之间都能把主机名解析为ip
[root@gc ~]$ cat /etc/hosts
# Do not remove the following line, or various programs
# that require network functionality will fail.
127.0.0.1 localhost.localdomain localhost
::1 localhost6.localdomain6 localhost6
192.168.2.101 rac1.localdomain rac1
192.168.2.102 rac2.localdomain rac2
192.168.2.100 gc.localdomain gc
3. 建立 hadoop 运行账号
在所有的节点创建 hadoop 运行账号
[root@gc ~]#groupadd hadoop
[root@gc ~]#useradd -g hadoop grid—注意此处一定要指定分组，不然可能会不能建立互信
[root@gc ~]# id grid
uid=501(grid) gid=54326(hadoop) groups=54326(hadoop)
[root@gc ~]#passwd grid
Changing password for user grid.
New UNIX password:
BAD PASSWORD: it is too short
Retype new UNIX password:
passwd: all authentication tokens updated successfully.
4. 配置 ssh 免密码连入
注意要以 hadoop 用户登录，在 hadoop 用户的主目录下进行操作。
每个节点做下面相同的操作
[hadoop@gc ~]$ ssh-keygen -t rsa
Generating public/private rsa key pair.
Enter file in which to save the key (/home/hadoop/.ssh/id_rsa):
Created directory ‘/home/hadoop/.ssh’.
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /home/hadoop/.ssh/id_rsa.
Your public key has been saved in /home/hadoop/.ssh/id_rsa.pub.
The key fingerprint is:
54:80:fd:77:6b:87:97:ce:0f:32:34:43:d1:d2:c2:0d hadoop@gc.localdomain
[hadoop@gc ~]$ cd .ssh
[hadoop@gc .ssh]$ ls
id_rsa id_rsa.pub
把各个节点的 authorized_keys 的内容互相拷贝加入到对方的此文件中，然后就可以免密码彼此 ssh 连入。
在其中一节点（gc）节点就可完成操作
[hadoop@gc .ssh]$ cat ~/.ssh/id_rsa.pub >> ~/.ssh/authorized_keys
[hadoop@gc .ssh]$ssh rac1 cat ~/.ssh/id_rsa.pub >> ~/.ssh/authorized_keys
The authenticity of host ‘rac1 (192.168.2.101)’ can’t be established.
RSA key fingerprint is 19:48:e0:0a:37:e1:2a:d5:ba:c8:7e:1b:37:c6:2f:0e.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added ‘rac1,192.168.2.101’ (RSA) to the list of known hosts.
hadoop@rac1’s password:
[hadoop@gc .ssh]$ssh rac2 cat ~/.ssh/id_rsa.pub >> ~/.ssh/authorized_keys
The authenticity of host ‘rac2 (192.168.2.102)’ can’t be established.
RSA key fingerprint is 19:48:e0:0a:37:e1:2a:d5:ba:c8:7e:1b:37:c6:2f:0e.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added ‘rac2,192.168.2.102’ (RSA) to the list of known hosts.
hadoop@rac2’s password:
[hadoop@gc .ssh]$scp ~/.ssh/authorized_keys rac1:~/.ssh/authorized_keys
hadoop@rac1’s password:
authorized_keys 100% 1213 1.2KB/s 00:00
[hadoop@gc .ssh]$scp ~/.ssh/authorized_keys rac2:~/.ssh/authorized_keys
hadoop@rac2’s password:
authorized_keys 100% 1213 1.2KB/s 00:00
[hadoop@gc .ssh]$ ll
总计 16
-rw-rw-r– 1 hadoop hadoop 1213 10-30 09:18 authorized_keys
-rw——- 1 hadoop hadoop 1675 10-30 09:05 id_rsa
-rw-r–r– 1 hadoop hadoop 403 10-30 09:05 id_rsa.pub
—分别测试连接
[grid@gc .ssh]$ ssh rac1 date
2012年 11 月 18日星期日 01:35:39 CST
[grid@gc .ssh]$ ssh rac2 date
2012年 10 月 30日星期二 09:52:46 CST
—可以看到这步和配置 oracle RAC 中使用 SSH 建立用户等效性步骤是一样的。
5. 解压 hadoop 安装包
—可先一某节点解压配置文件
[grid@gc ~]$ ll
总计 43580
-rw-r–r– 1 grid hadoop 44575568 2012-11-19 hadoop-0.20.2.tar.gz
[grid@gc ~]$ tar xzvf /home/grid/hadoop-0.20.2.tar.gz
[grid@gc ~]$ ll
总计 43584
drwxr-xr-x 12 grid hadoop 4096 2010-02-19 hadoop-0.20.2
-rw-r–r– 1 grid hadoop 44575568 2012-11-19 hadoop-0.20.2.tar.gz
—在各节点安装jdk
[root@gc ~]# ./jdk-6u18-linux-x64-rpm.bin
相关阅读：
Ubuntu 13.04 上搭建 Hadoop 环境 http://www.linuxidc.com/Linux/2013-06/86106.htm
Ubuntu 12.10 +Hadoop 1.2.1 版本集群配置 http://www.linuxidc.com/Linux/2013-09/90600.htm
Ubuntu 上搭建 Hadoop 环境（单机模式 + 伪分布模式）http://www.linuxidc.com/Linux/2013-01/77681.htm
Ubuntu 下 Hadoop 环境的配置 http://www.linuxidc.com/Linux/2012-11/74539.htm
单机版搭建 Hadoop 环境图文教程详解 http://www.linuxidc.com/Linux/2012-02/53927.htm
搭建 Hadoop 环境（在 Winodws 环境下用虚拟机虚拟两个 Ubuntu 系统进行搭建）http://www.linuxidc.com/Linux/2011-12/48894.htm
6. Hadoop配置有关文件
n 配置hadoop-env.sh
[root@gc conf]# pwd
/root/hadoop-0.20.2/conf
—修改 jdk 安装路径
[root@gc conf]vi hadoop-env.sh
export JAVA_HOME=/usr/java/jdk1.6.0_18
n 配置 namenode，修改site 文件
—修改 core-site.xml 文件
[gird@gc conf]#vi core-site.xml
<?xml version=”1.0″?>
<?xml-stylesheet type=”text/xsl” href=”https://www.linuxidc.com/Linux/2014-02/configuration.xsl”?>
<!– Put site-specific property overrides in this file. –>
<configuration>
<property>
<name>fs.default.name</name>
<value>hdfs://gc:9000</value>#完全分布式不能用 localhost, 要用 master 节点的 IP 或机器名
</property>
<property>
<name>hadoop.tmp.dir</name>
<value>/home/grid/hadoop/tmp</value>
</property>
</configuration>
注：fs.default.name NameNode的 IP 地址和端口
—修改 hdfs-site.xml 文件
[gird@gc conf]#vi hdfs-site.xml
<?xml version=”1.0″?>
<?xml-stylesheet type=”text/xsl” href=”https://www.linuxidc.com/Linux/2014-02/configuration.xsl”?>
<!– Put site-specific property overrides in this file. –>
<configuration>
<property>
<name>dfs.data.dir</name>
<value>/home/grid/hadoop-0.20.2/data</value>—注意此目录必需已经创建并能读写
</property>
<property>
<name>dfs.replication</name>
<value>2</value>
</property>
</configuration>
hdfs-site.xml文件中常用配置参数：
—修改 mapred-site.xml 文件
[gird@gc conf]#vi mapred-site.xml
<?xml version=”1.0″?>
<?xml-stylesheet type=”text/xsl” href=”https://www.linuxidc.com/Linux/2014-02/configuration.xsl”?>
<!– Put site-specific property overrides in this file. –>
<configuration>
<property>
<name>mapred.job.tracker</name>
<value>gc:9001</value>
</property>
</configuration>
mapred-site.xml文件中常用配置参数
n 配置 masters 和slaves文件
[grid@gc conf]$ vi masters
gc
[grid@gc conf]$ vi slaves
rac1
rac2
n 向各节点复制hadoop
—把 gc 主机上面 hadoop 配置好文件分别 copy 到各节点
—注意：复制到其它的节点后配置文件中要修改为此节点的IP
[grid@gc conf]$ scp -r hadoop-0.20.2 rac1:/home/grid/
[grid@gc conf]$ scp -r hadoop-0.20.2 rac2:/home/grid/
Hadoop模式介绍
单机模式：安装简单，几乎不用作任何配置，但仅限于调试用途
伪分布模式：在单节点上同时启动 namenode、datanode、jobtracker、tasktracker、secondary namenode 等5个进程，模拟分布式运行的各个节点
完全分布式模式：正常的 Hadoop 集群，由多个各司其职的节点构成
安装环境
操作平台：vmware2
操作系统：Oracle linux 5.6
软件版本：hadoop-0.22.0,jdk-6u18
集群架构：3 node，master node(gc),slave node(rac1,rac2)
安装步骤
1. 下载 Hadoop 和jdk：
http://mirror.bit.edu.cn/apache/hadoop/common/
如：hadoop-0.22.0
2. 配置 hosts 文件
所有的节点（gc,rac1,rac2）都修改/etc/hosts，使彼此之间都能把主机名解析为ip
[root@gc ~]$ cat /etc/hosts
# Do not remove the following line, or various programs
# that require network functionality will fail.
127.0.0.1 localhost.localdomain localhost
::1 localhost6.localdomain6 localhost6
192.168.2.101 rac1.localdomain rac1
192.168.2.102 rac2.localdomain rac2
192.168.2.100 gc.localdomain gc
3. 建立 hadoop 运行账号
在所有的节点创建 hadoop 运行账号
[root@gc ~]#groupadd hadoop
[root@gc ~]#useradd -g hadoop grid—注意此处一定要指定分组，不然可能会不能建立互信
[root@gc ~]# id grid
uid=501(grid) gid=54326(hadoop) groups=54326(hadoop)
[root@gc ~]#passwd grid
Changing password for user grid.
New UNIX password:
BAD PASSWORD: it is too short
Retype new UNIX password:
passwd: all authentication tokens updated successfully.
4. 配置 ssh 免密码连入
注意要以 hadoop 用户登录，在 hadoop 用户的主目录下进行操作。
每个节点做下面相同的操作
[hadoop@gc ~]$ ssh-keygen -t rsa
Generating public/private rsa key pair.
Enter file in which to save the key (/home/hadoop/.ssh/id_rsa):
Created directory ‘/home/hadoop/.ssh’.
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /home/hadoop/.ssh/id_rsa.
Your public key has been saved in /home/hadoop/.ssh/id_rsa.pub.
The key fingerprint is:
54:80:fd:77:6b:87:97:ce:0f:32:34:43:d1:d2:c2:0d hadoop@gc.localdomain
[hadoop@gc ~]$ cd .ssh
[hadoop@gc .ssh]$ ls
id_rsa id_rsa.pub
把各个节点的 authorized_keys 的内容互相拷贝加入到对方的此文件中，然后就可以免密码彼此 ssh 连入。
在其中一节点（gc）节点就可完成操作
[hadoop@gc .ssh]$ cat ~/.ssh/id_rsa.pub >> ~/.ssh/authorized_keys
[hadoop@gc .ssh]$ssh rac1 cat ~/.ssh/id_rsa.pub >> ~/.ssh/authorized_keys
The authenticity of host ‘rac1 (192.168.2.101)’ can’t be established.
RSA key fingerprint is 19:48:e0:0a:37:e1:2a:d5:ba:c8:7e:1b:37:c6:2f:0e.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added ‘rac1,192.168.2.101’ (RSA) to the list of known hosts.
hadoop@rac1’s password:
[hadoop@gc .ssh]$ssh rac2 cat ~/.ssh/id_rsa.pub >> ~/.ssh/authorized_keys
The authenticity of host ‘rac2 (192.168.2.102)’ can’t be established.
RSA key fingerprint is 19:48:e0:0a:37:e1:2a:d5:ba:c8:7e:1b:37:c6:2f:0e.
Are you sure you want to continue connecting (yes/no)? yes
Warning: Permanently added ‘rac2,192.168.2.102’ (RSA) to the list of known hosts.
hadoop@rac2’s password:
[hadoop@gc .ssh]$scp ~/.ssh/authorized_keys rac1:~/.ssh/authorized_keys
hadoop@rac1’s password:
authorized_keys 100% 1213 1.2KB/s 00:00
[hadoop@gc .ssh]$scp ~/.ssh/authorized_keys rac2:~/.ssh/authorized_keys
hadoop@rac2’s password:
authorized_keys 100% 1213 1.2KB/s 00:00
[hadoop@gc .ssh]$ ll
总计 16
-rw-rw-r– 1 hadoop hadoop 1213 10-30 09:18 authorized_keys
-rw——- 1 hadoop hadoop 1675 10-30 09:05 id_rsa
-rw-r–r– 1 hadoop hadoop 403 10-30 09:05 id_rsa.pub
—分别测试连接
[grid@gc .ssh]$ ssh rac1 date
2012年 11 月 18日星期日 01:35:39 CST
[grid@gc .ssh]$ ssh rac2 date
2012年 10 月 30日星期二 09:52:46 CST
—可以看到这步和配置 oracle RAC 中使用 SSH 建立用户等效性步骤是一样的。
5. 解压 hadoop 安装包
—可先一某节点解压配置文件
[grid@gc ~]$ ll
总计 43580
-rw-r–r– 1 grid hadoop 44575568 2012-11-19 hadoop-0.20.2.tar.gz
[grid@gc ~]$ tar xzvf /home/grid/hadoop-0.20.2.tar.gz
[grid@gc ~]$ ll
总计 43584
drwxr-xr-x 12 grid hadoop 4096 2010-02-19 hadoop-0.20.2
-rw-r–r– 1 grid hadoop 44575568 2012-11-19 hadoop-0.20.2.tar.gz
—在各节点安装jdk
[root@gc ~]# ./jdk-6u18-linux-x64-rpm.bin
相关阅读：
Ubuntu 13.04 上搭建 Hadoop 环境 http://www.linuxidc.com/Linux/2013-06/86106.htm
Ubuntu 12.10 +Hadoop 1.2.1 版本集群配置 http://www.linuxidc.com/Linux/2013-09/90600.htm
Ubuntu 上搭建 Hadoop 环境（单机模式 + 伪分布模式）http://www.linuxidc.com/Linux/2013-01/77681.htm
Ubuntu 下 Hadoop 环境的配置 http://www.linuxidc.com/Linux/2012-11/74539.htm
单机版搭建 Hadoop 环境图文教程详解 http://www.linuxidc.com/Linux/2012-02/53927.htm
搭建 Hadoop 环境（在 Winodws 环境下用虚拟机虚拟两个 Ubuntu 系统进行搭建）http://www.linuxidc.com/Linux/2011-12/48894.htm
7. 格式化namenode
—分别在各节点进行格式化
[grid@rac2 bin]$ pwd
/home/grid/Hadoop-0.20.2/bin
[grid@gc bin]$ ./hadoop namenode –format
12/10/31 08:03:31 INFO namenode.NameNode: STARTUP_MSG:
/************************************************************
STARTUP_MSG: Starting NameNode
STARTUP_MSG: host = gc.localdomain/192.168.2.100
STARTUP_MSG: args = [-format]
STARTUP_MSG: version = 0.20.2
STARTUP_MSG: build = https://svn.apache.org/repos/asf/hadoop/common/branches/branch-0.20 -r 911707; compiled by ‘chrisdo’ on Fri Feb 19 08:07:34 UTC 2010
************************************************************/
12/10/31 08:03:31 INFO namenode.FSNamesystem: fsOwner=grid,hadoop
12/10/31 08:03:31 INFO namenode.FSNamesystem: supergroup=supergroup
12/10/31 08:03:31 INFO namenode.FSNamesystem: isPermissionEnabled=true
12/10/31 08:03:32 INFO common.Storage: Image file of size 94 saved in 0 seconds.
12/10/31 08:03:32 INFO common.Storage: Storage directory /tmp/hadoop-grid/dfs/name has been successfully formatted.
12/10/31 08:03:32 INFO namenode.NameNode: SHUTDOWN_MSG:
/************************************************************
SHUTDOWN_MSG: Shutting down NameNode at gc.localdomain/192.168.2.100
************************************************************/
8. 启动hadoop
—在 master 节点启动 hadoop 守护进程
[grid@gc bin]$ pwd
/home/grid/hadoop-0.20.2/bin
[grid@gc bin]$./start-all.sh
starting namenode, logging to /home/grid/hadoop-0.20.2/bin/../logs/hadoop-grid-namenode-gc.localdomain.out
rac2: starting datanode, logging to /home/grid/hadoop-0.20.2/bin/../logs/hadoop-grid-datanode-rac2.localdomain.out
rac1: starting datanode, logging to /home/grid/hadoop-0.20.2/bin/../logs/hadoop-grid-datanode-rac1.localdomain.out
The authenticity of host ‘gc (192.168.2.100)’ can’t be established.
RSA key fingerprint is 8e:47:42:44:bd:e2:28:64:10:40:8e:b5:72:f9:6c:82.
Are you sure you want to continue connecting (yes/no)? yes
gc: Warning: Permanently added ‘gc,192.168.2.100’ (RSA) to the list of known hosts.
gc: starting secondarynamenode, logging to /home/grid/hadoop-0.20.2/bin/../logs/hadoop-grid-secondarynamenode-gc.localdomain.out
starting jobtracker, logging to /home/grid/hadoop-0.20.2/bin/../logs/hadoop-grid-jobtracker-gc.localdomain.out
rac2: starting tasktracker, logging to /home/grid/hadoop-0.20.2/bin/../logs/hadoop-grid-tasktracker-rac2.localdomain.out
rac1: starting tasktracker, logging to /home/grid/hadoop-0.20.2/bin/../logs/hadoop-grid-tasktracker-rac1.localdomain.out
9. 用 jps 检验各后台进程是否成功启动
—在 master 节点查看后台进程
[grid@gc bin]$ /usr/java/jdk1.6.0_18/bin/jps
27462 NameNode
29012 Jps
27672 JobTracker
27607 SecondaryNameNode
—在 slave 节点查看后台进程
[grid@rac1 conf]$/usr/java/jdk1.6.0_18/bin/jps
16722 Jps
16672 TaskTracker
16577 DataNode
[grid@rac2 conf]$/usr/java/jdk1.6.0_18/bin/jps
31451 DataNode
31547 TaskTracker
31608 Jps
测试连接：
http://192.168.2.100:50070/dfshealth.jsp
http://192.168.2.100:50030/jobtracker.jsp
10. 安装过程中遇到的问题
1) Ssh不能建立互信
建用户时不指定分组，Ssh不能建立互信，如下的步骤
[root@gc ~]#useradd grid
[root@gc ~]#passwd grid
解决：
创建新的用户组，创建用户时并指定此用户组。
[root@gc ~]#groupadd hadoop
[root@gc ~]#useradd -g hadoop grid
[root@gc ~]# id grid
uid=501(grid) gid=54326(hadoop) groups=54326(hadoop)
[root@gc ~]# passwd grid
2) 启动 hadoop 后，slave节点没有 datanode 进程
现象：
在 master 节点启动 hadoop 后，master节点进程正常，但 slave 节点没有 datanode 进程。
–Master节点正常
[grid@gc bin]$ /usr/java/jdk1.6.0_18/bin/jps
29843 Jps
29703 JobTracker
29634 SecondaryNameNode
29485 NameNode
—此时再在两 slave 节点查看进程，发现还是没有 datanode 进程
[grid@rac1 bin]$ /usr/java/jdk1.6.0_18/bin/jps
5528 Jps
3213 TaskTracker
[grid@rac2 bin]$ /usr/java/jdk1.6.0_18/bin/jps
30518 TaskTracker
30623 Jps
原因：
—回头查看在 master 节点启动 hadoop 时的输出日志，在 slave 节点找到启动 datanode 进程的日志
[grid@rac2 logs]$ pwd
/home/grid/hadoop-0.20.2/logs
[grid@rac1 logs]$ more hadoop-grid-datanode-rac1.localdomain.log
/************************************************************
STARTUP_MSG: Starting DataNode
STARTUP_MSG: host = rac1.localdomain/192.168.2.101
STARTUP_MSG: args = []
STARTUP_MSG: version = 0.20.2
STARTUP_MSG: build = https://svn.apache.org/repos/asf/hadoop/common/branches/branch-0.20 -r 911707; compiled by ‘chrisdo’ on Fri Feb 19 08:07:34 UTC 2010
************************************************************/
2012-11-18 07:43:33,513WARN org.apache.hadoop.hdfs.server.datanode.DataNode: Invalid directory in dfs.data.dir: can not create directory: /usr/hadoop-0.20.2/data
2012-11-18 07:43:33,513 ERROR org.apache.hadoop.hdfs.server.datanode.DataNode: All directories in dfs.data.dir are invalid.
2012-11-18 07:43:33,571 INFO org.apache.hadoop.hdfs.server.datanode.DataNode: SHUTDOWN_MSG:
/************************************************************
SHUTDOWN_MSG: Shutting down DataNode at rac1.localdomain/192.168.2.101
************************************************************/
—发现是 hdfs-site.xml配置文件的目录 data 目录没有创建
解决：
在各节点创建 hdfs 的 data 目录，并修改 hdfs-site.xml 配置文件参数
[grid@gc ~]# mkdir -p /home/grid/hadoop-0.20.2/data
[grid@gc conf]#vi hdfs-site.xml
<?xml version=”1.0″?>
<?xml-stylesheet type=”text/xsl” href=”https://www.linuxidc.com/Linux/2014-02/configuration.xsl”?>
<!– Put site-specific property overrides in this file. –>
<configuration>
<property>
<name>dfs.data.dir</name>
<value>/home/grid/hadoop-0.20.2/data</value>—注意此目录必需已经创建并能读写
</property>
<property>
<name>dfs.replication</name>
<value>2</value>
</property>
</configuration>
– 重新启动 hadoop，slave 进程正常
[grid@gc bin]$ ./stop-all.sh
[grid@gc bin]$ ./start-all.sh
3) Warning: $HADOOP_HOME is deprecated. hadoop1.0.1 解决方法
hadoop 1.0.1 版本执行 hadoop 命令的时候，经常出现
Warning: $HADOOP_HOME is deprecated.
经过查看 hadoop-1.0.1 的 hadoop 和 hadoop-config.sh 脚本，发现对于 HADDP_HOME 做了判断
解决方法如下：
1. 在配置文件中找到 if fi 语句，注释掉。（不推荐）
2. 在 HOME 的目录编辑.bash_profile，添加一个环境变量。
export HADOOP_HOME_WARN_SUPPRESS=1
更多 Hadoop 相关信息见Hadoop 专题页面 http://www.linuxidc.com/topicnews.aspx?tid=13
