Hadoop添加datanode或者tasktracker节点

1 规划新添加的hadoop节点的角色和配置

1.1 角色slave: 即datanode节点或者tasktracker节点1.2 配置主机名：hadoop03IP: 192.168.88.173hadoop用户：xiaoyu

2. 部署新的节点
2.1 安装操作系统2.3 关闭不必要的服务建议只保留以下服务：abrt-ccpp abrt-oops autofs crond haldaemon lvm2-monitor mdmonitor messagebus netfs network nfslock ntpd portreserve rsyslog sshd udev-post2.4 网络配置2.4.1 网卡地址示例配置文件如下，请根据实际所处的网络配置。# cat /etc/sysconfig/network-scripts/ifcfg-eth0DEVICE=eth0TYPE=EthernetONBOOT=yesNM_CONTROLLED=noBOOTPROTO=noneIPADDR=192.168.88.173NETMASK=255.255.255.0GATEWAY=192.168.88.2DNS1=192.168.88.2IPV6INIT=noUSERCTL=no2.4.2 修改主机名# sudo vim /etc/sysconfig/network 修改HOSTNAME值为主机名HOSTNAME=hadoop03# hostname hadoop032.4.3 配置密钥对[xiaoyu@hadoop03 ~]$ ssh-keygen -t rsa
Generating public/private rsa key pair.
Enter file in which to save the key (/home/xiaoyu/.ssh/id_rsa):
Enter passphrase (empty for no passphrase):
Enter same passphrase again:
Your identification has been saved in /home/xiaoyu/.ssh/id_rsa.
Your public key has been saved in /home/xiaoyu/.ssh/id_rsa.pub.
The key fingerprint is:
45:41:8d:17:3b:0c:20:e0:5d:3f:38:ed:1f:e6:b9:7a xiaoyu@hadoop03
The key's randomart image is:
+--[ RSA 2048]----+
| ... oo=+.. |
| . . o =.oo. |
| . . o =.+ |
| + . . |
| S . o |
| + o |
| + |
| E. |
| .o. |
+-----------------+
[xiaoyu@hadoop03 ~]$可以把这个操作写成一行命令，甚至写到脚本中：$ expect -c "spawn ssh-keygen ; set timeout 5; expect \":\"; send \"\r\n\"; set timeout 3; expect \":\"; send \"\r\n\";set timeout 3; expect \":\"; send \"\r\n\"; expect eof;"
2.4.4 配置ssh免密码认证看到过许多大牛，都是远程scp把公钥拷贝来拷贝去的。其实openssh客户端应用程序包已经提供了专门的命令来处理这个操作。[xiaoyu@hadoop03 ~]$ ssh-copy-id -i .ssh/id_rsa.pub 192.168.88.171The authenticity of host '192.168.88.171 (192.168.88.171)' can't be established.RSA key fingerprint is a8:24:3f:34:86:f3:46:67:c0:a6:b0:42:86:a2:f2:c9.Are you sure you want to continue connecting (yes/no)? yesWarning: Permanently added '192.168.88.171' (RSA) to the list of known hosts.Address 192.168.88.171 maps to localhost, but this does not map back to the address - POSSIBLE BREAK-IN ATTEMPT!xiaoyu@192.168.88.171's password: Now try logging into the machine, with "ssh '192.168.88.171'", and check in: .ssh/authorized_keysto make sure we haven't added extra keys that you weren't expecting.[xiaoyu@hadoop03 ~]$
3. 在hadoop集群节点上配置

3.1 修改hosts节点把新的集群节点的主机名和IP对应关系都放到hosts，便于本地解析
# sudo vim /etc/hosts
增加如下行：
192.168.88.171 hadoop01
192.168.88.172 hadoop02192.168.88.173 hadoop03可以通过ping <主机名>做简单测试3.2 添加ssh免密码认证方法和2.4.4 中的方法是一致的。3.3 修改conf/slave$ vim conf/slaveshadoop02
hadoop033.4 同步配置文件到新节点上[xiaoyu@hadoop01 hadoop-1.1.2]$ scp -r conf hadoop03:~/hadoop-1.1.2/log4j.properties 100% 4441 4.3KB/s 00:00 capacity-scheduler.xml 100% 7457 7.3KB/s 00:00 configuration.xsl 100% 535 0.5KB/s 00:00 fair-scheduler.xml 100% 327 0.3KB/s 00:00 hdfs-site.xml 100% 319 0.3KB/s 00:00 slaves 100% 18 0.0KB/s 00:00 ssl-server.xml.example 100% 1195 1.2KB/s 00:00 hadoop-policy.xml 100% 4644 4.5KB/s 00:00 taskcontroller.cfg 100% 382 0.4KB/s 00:00 mapred-queue-acls.xml 100% 2033 2.0KB/s 00:00 ssl-client.xml.example 100% 1243 1.2KB/s 00:00 masters 100% 9 0.0KB/s 00:00 core-site.xml 100% 441 0.4KB/s 00:00 hadoop-env.sh 100% 2271 2.2KB/s 00:00 hadoop-metrics2.properties 100% 1488 1.5KB/s 00:00 mapred-site.xml 100% 261 0.3KB/s 00:00

4. 启动新节点

4.1 在新节点启动集群服务[xiaoyu@hadoop03 hadoop-1.1.2]$ bin/hadoop-daemon.sh start datanode
starting datanode, logging to /home/xiaoyu/hadoop-1.1.2/libexec/../logs/hadoop-xiaoyu-datanode-hadoop03.out
[xiaoyu@hadoop03 hadoop-1.1.2]$ bin/hadoop-daemon.sh start tasktracker
starting tasktracker, logging to /home/xiaoyu/hadoop-1.1.2/libexec/../logs/hadoop-xiaoyu-tasktracker-hadoop03.out

5. 检查新节点的启动情况

在这里hadoop01为namenode节点这里有三种方法，当然执行命令的方法最简便。5.1 Namenode状态页面:http://hadoop01:50070



具体信息如下图

5.2 Jobtracker状态页面:http://hadoop01:50030

具体信息如下图：

5.3 任意节点为上执行$ bin/hadoop dfsadmin -report Configured Capacity: 32977600512 (30.71 GB)Present Capacity: 20209930240 (18.82 GB)DFS Remaining: 20003794944 (18.63 GB)DFS Used: 206135296 (196.59 MB)DFS Used%: 1.02%Under replicated blocks: 1Blocks with corrupt replicas: 0Missing blocks: 0-------------------------------------------------Datanodes available: 2 (2 total, 0 dead)Name: 192.168.88.172:50010Decommission Status : NormalConfigured Capacity: 16488800256 (15.36 GB)DFS Used: 205955072 (196.41 MB)Non DFS Used: 6369054720 (5.93 GB)DFS Remaining: 9913790464(9.23 GB)DFS Used%: 1.25%DFS Remaining%: 60.12%Last contact: Fri Sep 13 03:35:51 CST 2013
Name: 192.168.88.173:50010Decommission Status : NormalConfigured Capacity: 16488800256 (15.36 GB)DFS Used: 180224 (176 KB)Non DFS Used: 6398615552 (5.96 GB)DFS Remaining: 10090004480(9.4 GB)DFS Used%: 0%DFS Remaining%: 61.19%Last contact: Fri Sep 13 03:35:50 CST 2013

6. 使正在运行的计算分布到新的数据节点上

[xiaoyu@hadoop01 hadoop-1.1.2]$ ./bin/start-balancer.sh starting balancer, logging to /home/xiaoyu/hadoop-1.1.2/libexec/../logs/hadoop-xiaoyu-balancer-hadoop01.out[xiaoyu@hadoop01 hadoop-1.1.2]$ 这个脚本很有用，大家也可以根据实际需要修改这个脚本。

7. 参考资料

Is there a way to add nodes to a running Hadoop cluster?

http://stackoverflow.com/questions/13159184/is-there-a-way-to-add-nodes-to-a-running-hadoop-cluster
1> Update the /etc/hadoop/conf/slaves list with the new node-name2> Sync the full configuration /etc/hadoop/conf to the new datanode from the Namenode. If the file system isn't shared. 2> Restart all the hadoop services on Namenode/Tasktracker and all the services on the new Datanode. 3> Verify the new datanode from the browser http://namenode:500704> Run the balancer script to readjust the data between the nodes.