如何完全分布式安装Hadoop
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Hadoop完全分布式模式安装步骤
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：
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
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="configuration.xsl" >
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="configuration.xsl" >
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="configuration.xsl" >
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/
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 = ; 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
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 = ; compiled by 'chrisdo' on Fri Feb 19 08:07:34 UTC 2010
************************************************************/
2012-11-18 07:43:33,513 WARN 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="configuration.xsl" >
--重新启动hadoop，slave进程正常
[grid@gc bin]$ ./stop-all.sh
[grid@gc bin]$ ./start-all.sh
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