hadoop的三种方式
时间同步：date
火墙：iptables
解析：hosts
主机：192.168.2.149
节点：192.168.2.150
192.168.2.125
192.168.2.126
rsync和ssh
网站：http://hadoop.apache.org/
有三种方式：单个节点
尾部式 （ 用于测试 ）
完全分布式
～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～
1.基本安装及单个节点
(1)下载 lftp i
get hadoop-1.2.1.tar.gz jdk-6u32-linux-x64.bin
(2)java：*sh jdk-6u32-linux-x64.bin
结果：Java(TM) SE Development Kit 6 successfully installed.
Product Registration is FREE and includes many benefits:
* Notification of new versions, patches, and updates
* Special offers on Oracle products, services and training
* Access to early releases and documentation
Product and system data will be collected. If your configuration
supports a browser, the JDK Product Registration form will
be presented. If you do not register, none of this information
will be saved. You may also register your JDK later by
opening the register.html file (located in the JDK installation
directory) in a browser.
For more information on what data Registration collects and
how it is managed and used, see:
http://java.sun.com/javase/registration/JDKRegistrationPrivacy.html
Press Enter to continue.....
Done.
查看：ls
结果：hadoop-1.2.1.tar.gz jdk1.6.0_32 （ 多了此目录 ） jdk-6u32-linux-x64.bin
安装：tar zfx hadoop-1.2.1.tar.gz
移动：mv jdk1.6.0_32/ hadoop-1.2.1/jdk （ 为了方便一次性端走服务 ）
链接：ln -s hadoop-1.2.1 hadoop （ 为了方便以后的更新 ）
（3）配置 vim hadoop/conf/hadoop-env.sh
内容：export JAVA_HOME=/root/hadoop/jdk（ 9行 java所在的目录 ）
（4）测试
1.输入 *mkdir hadoop/input
*cp /root/hadoop/conf/*.xml /root/hadoop/input/
*ls /root/hadoop/input/
结果：capacity-scheduler.xml fair-scheduler.xml hdfs-site.xml mapred-site.xml
core-site.xml hadoop-policy.xml mapred-queue-acls.xml
2.输出 *cd /root/hadoop
*bin/hadoop jar hadoop-examples-1.2.1.jar （ 查看所支持的功能 ）
结果：An example program must be given as the first argument.
Valid program names are:
aggregatewordcount: An Aggregate based map/reduce program that counts the words in the input files.
aggregatewordhist: An Aggregate based map/reduce program that computes the histogram of the words in the input files.
dbcount: An example job that count the pageview counts from a database.
grep: A map/reduce program that counts the matches of a regex in the input. （ 过滤 ）
join: A job that effects a join over sorted, equally partitioned datasets
multifilewc: A job that counts words from several files.
pentomino: A map/reduce tile laying program to find solutions to pentomino problems.
pi: A map/reduce program that estimates Pi using monte-carlo method.
randomtextwriter: A map/reduce program that writes 10GB of random textual data per node.
randomwriter: A map/reduce program that writes 10GB of random data per node.
secondarysort: An example defining a secondary sort to the reduce.
sleep: A job that sleeps at each map and reduce task.
sort: A map/reduce program that sorts the data written by the random writer.
sudoku: A sudoku solver.
teragen: Generate data for the terasort
terasort: Run the terasort
teravalidate: Checking results of terasort
wordcount: A map/reduce program that counts the words in the input files.
*bin/hadoop jar hadoop-examples-1.2.1.jar grep input/ output 'dfs[a-z.]+' （ 把input的有dfs开头的过滤到output里，自动建立output目录 ）
结果：14/08/05 09:50:28 INFO mapred.JobClient: Virtual memory (bytes) snapshot=0
14/08/05 09:50:28 INFO mapred.JobClient: Map output records=1
*ls /root/hadoop/output/
结果：part-00000 _SUCCESS
～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～
2.尾分布式文件系统
/root/hadoop/bin/stop-all.sh
(1)ssh （ 实现无密钥验证 ）
*ssh-keygen （ 获取密钥，空格即可 ）
结果：Generating public/private rsa key pair.
Enter file in which to save the key (/root/.ssh/id_rsa): 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:
07:f2:66:76:2b:59:76:29:c9:d9:b1:50:0f:5a:e9:2d root@server149.example.com
The key's randomart image is:
+--[ RSA 2048]----+
| +. |
| +.o |
| . . o.... |
| o o =E+. |
| S X =. |
| + * + |
| o . |
| . |
| |
+-----------------+
*ssh-copy-id server149.example.com
结果：The authenticity of host 'server149.example.com (192.168.2.149)' can't be established.
RSA key fingerprint is 66:9e:7c:f4:48:10:e3:20:59:1e:e9:44:35:32:42:14.
Are you sure you want to continue connecting (yes/no)? yes ***
Warning: Permanently added 'server149.example.com,192.168.2.149' (RSA) to the list of known hosts.
root@server149.example.com's password: （ 输入密码 ）
Now try logging into the machine, with "ssh 'server149.example.com'", and check in:
.ssh/authorized_keys
to make sure we haven't added extra keys that you weren't expecting.
*ssh-copy-id localhost
结果：The authenticity of host 'localhost (::1)' can't be established.
RSA key fingerprint is 66:9e:7c:f4:48:10:e3:20:59:1e:e9:44:35:32:42:14.
Are you sure you want to continue connecting (yes/no)? yes ***
Warning: Permanently added 'localhost' (RSA) to the list of known hosts.
Now try logging into the machine, with "ssh 'localhost'", and check in:
.ssh/authorized_keys
to make sure we haven't added extra keys that you weren't expecting.
测试：ssh server149.example.com
结果：Last login: Tue Aug 5 08:44:19 2014 from 192.168.2.1
离开：logout
结果：Connection to server149.example.com closed.
网站：http://hadoop.apache.org/docs/r1.2.1/single_node_setup.html
（2）配置文件 *vim /root/hadoop/conf/core-site.xml
内容：<configuration>
<property>
<name>fs.default.name</name>
<value>hdfs://server149.example.com:9000</value>
</property>
</configuration>
*vim /root/hadoop/conf/hdfs-site.xml
内容：<configuration>
<property>
<name>dfs.replication</name>
<value>1</value>
</property>
</configuration>
*vim /root/hadoop/conf/mapred-site.xml
内容：<configuration>
<property>
<name>mapred.job.tracker</name>
<value>server149.example.com:9001</value>
</property>
</configuration>
（3）解析 vim /etc/hosts
内容：192.168.2.149 server149.example.com
（4）格式化并开启服务
格式化： */root/hadoop/bin/hadoop namenode -format
结果：14/08/05 10:22:08 INFO namenode.NameNode: STARTUP_MSG:
/************************************************************
STARTUP_MSG: Starting NameNode
STARTUP_MSG: host = server149.example.com/192.168.2.149
STARTUP_MSG: args = [-format]
STARTUP_MSG: version = 1.2.1
STARTUP_MSG: build = https://svn.apache.org/repos/asf/hadoop/common/branches/branch-1.2 -r 1503152; compiled by 'mattf' on Mon Jul 22 15:23:09 PDT 2013
STARTUP_MSG: java = 1.6.0_32
************************************************************/
14/08/05 10:22:08 INFO util.GSet: Computing capacity for map BlocksMap
14/08/05 10:22:08 INFO util.GSet: VM type = 64-bit
14/08/05 10:22:08 INFO util.GSet: 2.0% max memory = 1013645312
14/08/05 10:22:08 INFO util.GSet: capacity = 2^21 = 2097152 entries
14/08/05 10:22:08 INFO util.GSet: recommended=2097152, actual=2097152
14/08/05 10:22:08 INFO namenode.FSNamesystem: fsOwner=root
14/08/05 10:22:08 INFO namenode.FSNamesystem: supergroup=supergroup
14/08/05 10:22:08 INFO namenode.FSNamesystem: isPermissionEnabled=true
14/08/05 10:22:08 INFO namenode.FSNamesystem: dfs.block.invalidate.limit=100
14/08/05 10:22:08 INFO namenode.FSNamesystem: isAccessTokenEnabled=false accessKeyUpdateInterval=0 min(s), accessTokenLifetime=0 min(s)
14/08/05 10:22:08 INFO namenode.FSEditLog: dfs.namenode.edits.toleration.length = 0
14/08/05 10:22:08 INFO namenode.NameNode: Caching file names occuring more than 10 times
14/08/05 10:22:09 INFO common.Storage: Image file /tmp/hadoop-root/dfs/name/current/fsimage of size 110 bytes saved in 0 seconds.
14/08/05 10:22:09 INFO namenode.FSEditLog: closing edit log: position=4, editlog=/tmp/hadoop-root/dfs/name/current/edits
14/08/05 10:22:09 INFO namenode.FSEditLog: close success: truncate to 4, editlog=/tmp/hadoop-root/dfs/name/current/edits
14/08/05 10:22:09 INFO common.Storage: Storage directory /tmp/hadoop-root/dfs/name has been successfully formatted.
14/08/05 10:22:09 INFO namenode.NameNode: SHUTDOWN_MSG:
/************************************************************
SHUTDOWN_MSG: Shutting down NameNode at server149.example.com/192.168.2.149
************************************************************
*/root/hadoop/bin/start-all.sh
结果：namenode running as process 2504. Stop it first.
localhost: starting datanode, logging to /root/hadoop-1.2.1/libexec/../logs/hadoop-root-datanode-server149.example.com.out
localhost: starting secondarynamenode, logging to /root/hadoop-1.2.1/libexec/../logs/hadoop-root-secondarynamenode-server149.example.com.out
jobtracker running as process 2674. Stop it first.
localhost: starting tasktracker, logging to /root/hadoop-1.2.1/libexec/../logs/hadoop-root-tasktracker-server149.example.com.out
（5）查看 /root/hadoop/jdk/bin/jps
结果：3183 TaskTracker
2674 JobTracker
3035 SecondaryNameNode
2932 DataNode
2504 NameNode
3276 Jps
3.测试
（1）网页监控 http://192.168.2.149:50070/dfshealth.jsp
http://192.168.2.149:50030/jobtracker.jsp
（2）测试 rm -fr /root/hadoop/output/
*建目录：test
/root/hadoop/bin/hadoop fs -mkdir test
查看：/root/hadoop/bin/hadoop fs -ls
结果：Found 1 items
drwxr-xr-x - root supergroup 0 2014-08-05 11:13 /user/root/test
*上传：传到test目录里
/root/hadoop/bin/hadoop fs -put /root/hadoop/conf/*.xml test
查看：/root/hadoop/bin/hadoop fs -ls test
结果：Found 7 items
-rw-r--r-- 1 root supergroup 7457 2014-08-05 11:15 /user/root/test/capacity-scheduler.xml
-rw-r--r-- 1 root supergroup 348 2014-08-05 11:15 /user/root/test/core-site.xml
-rw-r--r-- 1 root supergroup 327 2014-08-05 11:15 /user/root/test/fair-scheduler.xml
-rw-r--r-- 1 root supergroup 4644 2014-08-05 11:15 /user/root/test/hadoop-policy.xml
-rw-r--r-- 1 root supergroup 316 2014-08-05 11:15 /user/root/test/hdfs-site.xml
-rw-r--r-- 1 root supergroup 2033 2014-08-05 11:15 /user/root/test/mapred-queue-acls.xml
-rw-r--r-- 1 root supergroup 344 2014-08-05 11:15 /user/root/test/mapred-site.xml
*输出：cd /root/hadoop
bin/hadoop jar hadoop-examples-1.2.1.jar grep test output 'dfs[a-z.]+'
结果：14/08/05 11:16:57 INFO util.NativeCodeLoader: Loaded the native-hadoop library
14/08/05 11:16:57 WARN snappy.LoadSnappy: Snappy native library not loaded
14/08/05 11:16:57 INFO mapred.FileInputFormat: Total input paths to process : 7
14/08/05 11:16:58 INFO mapred.JobClient: Running job: job_201408051022_0001
14/08/05 11:16:59 INFO mapred.JobClient: map 0% reduce 0% ......
14/08/05 11:23:34 INFO mapred.JobClient: Virtual memory (bytes) snapshot=1445437440
14/08/05 11:23:34 INFO mapred.JobClient: Map output records=2
*查看：/root/hadoop/bin/hadoop fs -ls
结果：Found 2 items
drwxr-xr-x - root supergroup 0 2014-08-05 11:23 /user/root/output
drwxr-xr-x - root supergroup 0 2014-08-05 11:15 /user/root/test
/root/hadoop/bin/hadoop fs -cat output/*
结果：1 dfs.replication
1 dfsadmin
cat: File does not exist: /user/root/output/_logs
*下载：/root/hadoop/bin/hadoop fs -get output test （ 下载到本地 ）
查看：ll -d /root/hadoop/test/
结果：drwxr-xr-x 3 root root 4096 Aug 5 11:27 /root/hadoop/test/
cat /root/hadoop/test/*
结果：cat: /root/hadoop/test/_logs: Is a directory
1 dfs.replication
1 dfsadmin
*删除：rm -fr /root/hadoop/test/
/root/hadoop/bin/hadoop fs -rmr output
结果：Deleted hdfs://server149.example.com:9000/user/root/output
查看：/root/hadoop/bin/hadoop fs -ls
结果：Found 1 items
drwxr-xr-x - root supergroup 0 2014-08-05 11:15 /user/root/test
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
master slives
HDFS namenode datanode
mp jobtracker tasktracter
mfs：数据存储
HDFS：存储与计算。
～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～
3.完全式（ 服务分开，添加节点 ）
1.主机（ 149 ）
（1）停服务 */root/hadoop/bin/stop-all.sh
结果：stopping jobtracker
localhost: stopping tasktracker
stopping namenode
localhost: stopping datanode
localhost: stopping secondarynamenode
*/root/hadoop/jdk/bin/jps
结果：8675 Jps
（2）解析 vim /etc/hosts （ 都需要 ）
内容：192.168.2.125 server125.example.com
192.168.2.150 server150.example.com
192.168.2.149 server149.example.com
（3）ssh ssh-copy-id server150.example.com
ssh-copy-id server125.example.com
（4）配置文件vim /root/hadoop/conf/hdfs-site.xml
内容：<value>2</value> （ 9 ）
vim /root/hadoop/conf/masters
内容：server149.example.com
vim /root/hadoop/conf/slaves
内容：server150.example.com
server125.example.com
（5）复制给添加的节点 （ 添加的节点主机做链接 ）
scp -r /root/hadoop-1.2.1 server150.example.com:
scp -r /root/hadoop-1.2.1 server125.example.com:
（6）格式化 /root/hadoop/bin/hadoop namenode -format
结果：14/08/05 10:22:08 INFO namenode.NameNode: STARTUP_MSG:
/************************************************************
STARTUP_MSG: Starting NameNode
STARTUP_MSG: host = server149.example.com/192.168.2.149
STARTUP_MSG: args = [-format]
STARTUP_MSG: version = 1.2.1
STARTUP_MSG: build = https://svn.apache.org/repos/asf/hadoop/common/branches/branch-1.2 -r 1503152; compiled by 'mattf' on Mon Jul 22 15:23:09 PDT 2013
STARTUP_MSG: java = 1.6.0_32
************************************************************/
14/08/05 10:22:08 INFO util.GSet: Computing capacity for map BlocksMap
14/08/05 10:22:08 INFO util.GSet: VM type = 64-bit
14/08/05 10:22:08 INFO util.GSet: 2.0% max memory = 1013645312
14/08/05 10:22:08 INFO util.GSet: capacity = 2^21 = 2097152 entries
14/08/05 10:22:08 INFO util.GSet: recommended=2097152, actual=2097152
14/08/05 10:22:08 INFO namenode.FSNamesystem: fsOwner=root
14/08/05 10:22:08 INFO namenode.FSNamesystem: supergroup=supergroup
14/08/05 10:22:08 INFO namenode.FSNamesystem: isPermissionEnabled=true
14/08/05 10:22:08 INFO namenode.FSNamesystem: dfs.block.invalidate.limit=100
14/08/05 10:22:08 INFO namenode.FSNamesystem: isAccessTokenEnabled=false accessKeyUpdateInterval=0 min(s), accessTokenLifetime=0 min(s)
14/08/05 10:22:08 INFO namenode.FSEditLog: dfs.namenode.edits.toleration.length = 0
14/08/05 10:22:08 INFO namenode.NameNode: Caching file names occuring more than 10 times
14/08/05 10:22:09 INFO common.Storage: Image file /tmp/hadoop-root/dfs/name/current/fsimage of size 110 bytes saved in 0 seconds.
14/08/05 10:22:09 INFO namenode.FSEditLog: closing edit log: position=4, editlog=/tmp/hadoop-root/dfs/name/current/edits
14/08/05 10:22:09 INFO namenode.FSEditLog: close success: truncate to 4, editlog=/tmp/hadoop-root/dfs/name/current/edits
14/08/05 10:22:09 INFO common.Storage: Storage directory /tmp/hadoop-root/dfs/name has been successfully formatted.
14/08/05 10:22:09 INFO namenode.NameNode: SHUTDOWN_MSG:
/************************************************************
SHUTDOWN_MSG: Shutting down NameNode at server149.example.com/192.168.2.149
************************************************************
（7）开启服务/root/hadoop/bin/start-all.sh
结果：starting namenode, logging to /root/hadoop-1.2.1/libexec/../logs/hadoop-root-namenode-server149.example.com.out
server125.example.com: starting datanode, logging to /root/hadoop-1.2.1/libexec/../logs/hadoop-root-datanode-server125.example.com.out
server150.example.com: starting datanode, logging to /root/hadoop-1.2.1/libexec/../logs/hadoop-root-datanode-server150.example.com.out
server149.example.com: starting secondarynamenode, logging to /root/hadoop-1.2.1/libexec/../logs/hadoop-root-secondarynamenode-server149.example.com.out
starting jobtracker, logging to /root/hadoop-1.2.1/libexec/../logs/hadoop-root-jobtracker-server149.example.com.out
server150.example.com: starting tasktracker, logging to /root/hadoop-1.2.1/libexec/../logs/hadoop-root-tasktracker-server150.example.com.out
server125.example.com: starting tasktracker, logging to /root/hadoop-1.2.1/libexec/../logs/hadoop-root-tasktracker-server125.example.com.out
（8）查看服务/root/hadoop/jdk/bin/jps
结果：5721 JobTracker
5643 SecondaryNameNode
5832 Jps
5479 NameNode
（9）测试 */root/hadoop/bin/hadoop fs -put /root/hadoop/conf/ test
*/root/hadoop/bin/hadoop fs -ls
结果：Found 1 items
drwxr-xr-x - root supergroup 0 2014-08-05 11:54 /user/root/test
*/root/hadoop/bin/hadoop fs -ls test
结果：Found 17 items
-rw-r--r-- 2 root supergroup 7457 2014-08-05 11:54 /user/root/test/capacity-scheduler.xml
http://hadoop.apache.org/ -rw-r--r-- 2 root supergroup 1095 2014-08-05 11:54 /user/root/test/configuration.xsl
-rw-r--r-- 2 root supergroup 348 2014-08-05 11:54 /user/root/test/core-site.xml
-rw-r--r-- 2 root supergroup 327 2014-08-05 11:54 /user/root/test/fair-scheduler.xml
-rw-r--r-- 2 root supergroup 2428 2014-08-05 11:54 /user/root/test/hadoop-env.sh
-rw-r--r-- 2 root supergroup 2052 2014-08-05 11:54 /user/root/test/hadoop-metrics2.properties
-rw-r--r-- 2 root supergroup 4644 2014-08-05 11:54 /user/root/test/hadoop-policy.xml
-rw-r--r-- 2 root supergroup 316 2014-08-05 11:54 /user/root/test/hdfs-site.xml
-rw-r--r-- 2 root supergroup 5018 2014-08-05 11:54 /user/root/test/log4j.properties
-rw-r--r-- 2 root supergroup 2033 2014-08-05 11:54 /user/root/test/mapred-queue-acls.xml
-rw-r--r-- 2 root supergroup 344 2014-08-05 11:54 /user/root/test/mapred-site.xml
-rw-r--r-- 2 root supergroup 22 2014-08-05 11:54 /user/root/test/masters
-rw-r--r-- 2 root supergroup 44 2014-08-05 11:54 /user/root/test/slaves
-rw-r--r-- 2 root supergroup 2042 2014-08-05 11:54 /user/root/test/ssl-client.xml.example
-rw-r--r-- 2 root supergroup 1994 2014-08-05 11:54 /user/root/test/ssl-server.xml.example
-rw-r--r-- 2 root supergroup 3890 2014-08-05 11:54 /user/root/test/task-log4j.properties
-rw-r--r-- 2 root supergroup 382 2014-08-05 11:54 /user/root/test/taskcontroller.cfg
*/root/hadoop/bin/hadoop jar /root/hadoop/hadoop-examples-1.2.1.jar wordcount test output
*/root/hadoop/bin/hadoop fs -cat output/*
2.被添加的节点主机（ 150 ）
（1）解析 vim /etc/hosts （ 都需要 ）
内容：192.168.2.125 server125.example.com
192.168.2.150 server150.example.com
192.168.2.149 server149.example.com
（2）链接 ln -s hadoop-1.2.1/ hadoop
ln -s /root/hadoop/jdk/bin/jps /usr/local/sbin/
（3）查看服务 /root/hadoop/jdk/bin/jps
结果：1459 Jps
1368 TaskTracker
1300 DataNode
3.被添加的节点主机（ 125 ）
（1）解析 vim /etc/hosts （ 都需要 ）
内容：192.168.2.125 server125.example.com
192.168.2.150 server150.example.com
192.168.2.149 server149.example.com
（2）链接 ln -s hadoop-1.2.1/ hadoop
ln -s /root/hadoop/jdk/bin/jps /usr/local/sbin/
（3）查看服务 /root/hadoop/jdk/bin/jps
结果：1291 DataNode
1355 TaskTracker
1448 Jps
～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～
在线添加节点
当用的不是超级用户的时候：需要有一个存在的用户，uid必需是相同的，当时
1.主机：192.168.2.149
（1）节点配置 vim /root/hadoop/conf/slaves
内容：server126.example.com
（2）解析 vim /etc/hosts
内容：192.168.2.126 server126.example.com
192.168.2.149 server149.example.com
192.168.2.150 server150.example.com
192.168.2.125 server125.example.com
（3）ssh ssh-copy-id server126.example.com
ssh server126.example.com （ 直接链接上不需要输入密码 ）
（4）复制hadoop （ 复制完以后在添加的节点主机上做链接 2.1 2.2 ）
scp -r /root/hadoop-1.2.1 server126.example.com:
（5）大数据 *dd if=/dev/zero of=/root/hadoop/data1.file bs=1M count=500
结果：500+0 records in
500+0 records out
524288000 bytes (524 MB) copied, 43.1638 s, 12.1 MB/s
*dd if=/dev/zero of=/root/hadoop/data2.file bs=1M count=500
*dd if=/dev/zero of=/root/hadoop/data3.file bs=1M count=500
（6）上传数据 （ 上传完数据以后在添加的节点主机上开启服务并查看数据 2.3 2.4）
/root/hadoop/bin/hadoop fs -mkdir data
/root/hadoop/bin/hadoop fs -put /root/hadoop/data{1,2,3}.file data
（7）平衡数据 /root/hadoop/bin/start-balancer.sh
结果：starting balancer, logging to /root/hadoop-1.2.1/libexec/../logs/hadoop-root-balancer-server149.example.com.out
2.添加的节点主机：192.168.2.126
（1）链接 ln -s hadoop-1.2.1/ hadoop
ln -s /root/hadoop/jdk/bin/jps /usr/local/sbin/
（2）解析 vim /etc/hosts
内容：192.168.2.126 server126.example.com
192.168.2.149 server149.example.com
（3）开启服务 */root/hadoop/bin/hadoop-daemon.sh start datanode
结果：starting datanode, logging to /root/hadoop-1.2.1/libexec/../logs/hadoop-root-datanode-server126.example.com.out
*/root/hadoop/bin/hadoop-daemon.sh start tasktracker
结果：starting tasktracker, logging to /root/hadoop-1.2.1/libexec/../logs/hadoop-root-tasktracker-server126.example.com.out
*jps
结果：1714 TaskTracker
1783 Jps
1631 DataNode
（4）查看数据 /root/hadoop/bin/hadoop dfsadmin -report
结果：Configured Capacity: 15568306176 (14.5 GB)
Present Capacity: 10721746944 (9.99 GB)
DFS Remaining: 7550484480 (7.03 GB)
DFS Used: 3171262464 (2.95 GB)
DFS Used%: 29.58%
Under replicated blocks: 0
Blocks with corrupt replicas: 0
Missing blocks: 0
-------------------------------------------------
Datanodes available: 3 (3 total, 0 dead)
Name: 192.168.2.125:50010
Decommission Status : Normal
Configured Capacity: 5189435392 (4.83 GB)
DFS Used: 1137459200 (1.06 GB)
Non DFS Used: 1615728640 (1.5 GB)
DFS Remaining: 2436247552(2.27 GB)
DFS Used%: 21.92%
DFS Remaining%: 46.95%
Last contact: Tue Aug 05 15:36:01 CST 2014
Name: 192.168.2.126:50010
Decommission Status : Normal
Configured Capacity: 5189435392 (4.83 GB)
DFS Used: 651132928 (620.97 MB)
Non DFS Used: 1615208448 (1.5 GB)
DFS Remaining: 2923094016(2.72 GB)
DFS Used%: 12.55% *****
DFS Remaining%: 56.33%
Last contact: Tue Aug 05 15:36:01 CST 2014
Name: 192.168.2.150:50010
Decommission Status : Normal
Configured Capacity: 5189435392 (4.83 GB)
DFS Used: 1382670336 (1.29 GB)
Non DFS Used: 1615659008 (1.5 GB)
DFS Remaining: 2191106048(2.04 GB)
DFS Used%: 26.64%
DFS Remaining%: 42.22%
Last contact: Tue Aug 05 15:36:00 CST 2014
～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～～
在线删除节点
（1）修改配置 *vim /root/hadoop/conf/mapred-site.xml
内容：<configuration>
<property>
<name>mapred.job.tracker</name>
<value>server149.example.com:9001</value>
</property>
<property> （ 添加此模块 ）
<name>dfs.hosts.exclude</name>
<value>/root/hadoop/conf/exclude-host</value>
</property>
</configuration>
*vim /root/hadoop/conf/exclude-host
内容：server150.example.com （ 要删除节点的主机 ）
（2）刷新节点 /root/hadoop/bin/hadoop dfsadmin -refreshNodes
（3）查看 /root/hadoop/bin/hadoop dfsadmin -report
内容：Configured Capacity: 15568306176 (14.5 GB)
Present Capacity: 10594420391 (9.87 GB)
DFS Remaining: 7300513792 (6.8 GB)
DFS Used: 3293906599 (3.07 GB)
DFS Used%: 31.09%
Under replicated blocks: 20
Blocks with corrupt replicas: 0
Missing blocks: 0
-------------------------------------------------
Datanodes available: 3 (3 total, 0 dead)
Name: 192.168.2.125:50010
Decommission Status : Normal
Configured Capacity: 5189435392 (4.83 GB)
DFS Used: 1137459200 (1.06 GB)
Non DFS Used: 1674080256 (1.56 GB)
DFS Remaining: 2377895936(2.21 GB)
DFS Used%: 21.92%
DFS Remaining%: 45.82%
Last contact: Tue Aug 05 15:48:43 CST 2014
Name: 192.168.2.126:50010
Decommission Status : Normal
Configured Capacity: 5189435392 (4.83 GB)
DFS Used: 773777063 (737.93 MB)
Non DFS Used: 1684134233 (1.57 GB)
DFS Remaining: 2731524096(2.54 GB)
DFS Used%: 14.91%
DFS Remaining%: 52.64%
Last contact: Tue Aug 05 15:48:43 CST 2014
Name: 192.168.2.150:50010
Decommission Status : Decommission in progress *** （ Decommissioned ）
Configured Capacity: 5189435392 (4.83 GB)
DFS Used: 1382670336 (1.29 GB)
Non DFS Used: 1615671296 (1.5 GB)
DFS Remaining: 2191093760(2.04 GB)
DFS Used%: 26.64%
DFS Remaining%: 42.22%
Last contact: Tue Aug 05 15:48:42 CST 2014
