实践环境：
机器名 ip 作用 机器配置
主要过程
1.修改hosts
cat /etc/hosts
在master和slave上都修改，添加机器名和对应ip
2.ssh无密码登录本机和其他机器
3.JDK环境
http://nemogu.iteye.com/blog/1542361
4.安装hadoop
5.配置hadoop
6.运行hadoop
1) 在master上启动
bin下运行 ./start-all.sh
如果一切正常启动的话，jps应如下面示
在master上，jps
7786 NameNode
9969 Jps
8102 SecondaryNameNode
8196 JobTracker
9969 Jps
8102 SecondaryNameNode
8196 JobTracker
在slave上，jps
6654 TaskTracker
6707 Jps
6463 DataNode
6707 Jps
6463 DataNode
问题：
master上jps如下示
13136 SecondaryNameNode
13227 JobTracker
13530 Jps
slave上jps如下示
6654 TaskTracker
6707 Jps
6463 DataNode
即master上jps看不到namenode，可能namenode有问题，查看logs下namenode日志，如下示
2012-05-31 22:04:31,872 INFO org.apache.hadoop.hdfs.server.namenode.NameNode: STARTUP_MSG:
/************************************************************
STARTUP_MSG: Starting NameNode
STARTUP_MSG: host = guxu-Lenovo-B460/127.0.1.1
STARTUP_MSG: args = []
STARTUP_MSG: version = 1.0.3
STARTUP_MSG: build = https://svn.apache.org/repos/asf/hadoop/common/branches/branch-1.0 -r 1335192; compiled by 'hortonfo' on Tue May 8 20:31:25 UTC 2012
************************************************************/
2012-05-31 22:04:32,034 INFO org.apache.hadoop.metrics2.impl.MetricsConfig: loaded properties from hadoop-metrics2.properties
2012-05-31 22:04:32,046 INFO org.apache.hadoop.metrics2.impl.MetricsSourceAdapter: MBean for source MetricsSystem,sub=Stats registered.
2012-05-31 22:04:32,048 INFO org.apache.hadoop.metrics2.impl.MetricsSystemImpl: Scheduled snapshot period at 10 second(s).
2012-05-31 22:04:32,048 INFO org.apache.hadoop.metrics2.impl.MetricsSystemImpl: NameNode metrics system started
2012-05-31 22:04:32,237 INFO org.apache.hadoop.metrics2.impl.MetricsSourceAdapter: MBean for source ugi registered.
2012-05-31 22:04:32,242 WARN org.apache.hadoop.metrics2.impl.MetricsSystemImpl: Source name ugi already exists!
2012-05-31 22:04:32,258 INFO org.apache.hadoop.metrics2.impl.MetricsSourceAdapter: MBean for source jvm registered.
2012-05-31 22:04:32,259 INFO org.apache.hadoop.metrics2.impl.MetricsSourceAdapter: MBean for source NameNode registered.
2012-05-31 22:04:32,298 INFO org.apache.hadoop.hdfs.util.GSet: VM type = 32-bit
2012-05-31 22:04:32,298 INFO org.apache.hadoop.hdfs.util.GSet: 2% max memory = 17.77875 MB
2012-05-31 22:04:32,298 INFO org.apache.hadoop.hdfs.util.GSet: capacity = 2^22 = 4194304 entries
2012-05-31 22:04:32,298 INFO org.apache.hadoop.hdfs.util.GSet: recommended=4194304, actual=4194304
2012-05-31 22:04:32,335 INFO org.apache.hadoop.hdfs.server.namenode.FSNamesystem: fsOwner=guxu
2012-05-31 22:04:32,335 INFO org.apache.hadoop.hdfs.server.namenode.FSNamesystem: supergroup=supergroup
2012-05-31 22:04:32,335 INFO org.apache.hadoop.hdfs.server.namenode.FSNamesystem: isPermissionEnabled=true
2012-05-31 22:04:32,342 INFO org.apache.hadoop.hdfs.server.namenode.FSNamesystem: dfs.block.invalidate.limit=100
2012-05-31 22:04:32,342 INFO org.apache.hadoop.hdfs.server.namenode.FSNamesystem: isAccessTokenEnabled=false accessKeyUpdateInterval=0 min(s), accessTokenLifetime=0 min(s)
2012-05-31 22:04:32,674 INFO org.apache.hadoop.hdfs.server.namenode.FSNamesystem: Registered FSNamesystemStateMBean and NameNodeMXBean
2012-05-31 22:04:32,695 INFO org.apache.hadoop.hdfs.server.namenode.NameNode: Caching file names occuring more than 10 times
2012-05-31 22:04:32,700 INFO org.apache.hadoop.hdfs.server.common.Storage: Storage directory /home/guxu/hadoop_tmp_dir/dfs/name does not exist.
2012-05-31 22:04:32,702 ERROR org.apache.hadoop.hdfs.server.namenode.FSNamesystem: FSNamesystem initialization failed.
org.apache.hadoop.hdfs.server.common.InconsistentFSStateException: Directory /home/guxu/hadoop_tmp_dir/dfs/name is in an inconsistent state: storage directory does not exist or is not accessible.
at org.apache.hadoop.hdfs.server.namenode.FSImage.recoverTransitionRead(FSImage.java:303)
at org.apache.hadoop.hdfs.server.namenode.FSDirectory.loadFSImage(FSDirectory.java:100)
at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.initialize(FSNamesystem.java:388)
at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.<init>(FSNamesystem.java:362)
at org.apache.hadoop.hdfs.server.namenode.NameNode.initialize(NameNode.java:276)
at org.apache.hadoop.hdfs.server.namenode.NameNode.<init>(NameNode.java:496)
at org.apache.hadoop.hdfs.server.namenode.NameNode.createNameNode(NameNode.java:1279)
at org.apache.hadoop.hdfs.server.namenode.NameNode.main(NameNode.java:1288)
2012-05-31 22:04:32,704 ERROR org.apache.hadoop.hdfs.server.namenode.NameNode: org.apache.hadoop.hdfs.server.common.InconsistentFSStateException: Directory /home/guxu/hadoop_tmp_dir/dfs/name is in an inconsistent state: storage directory does not exist or is not accessible.
at org.apache.hadoop.hdfs.server.namenode.FSImage.recoverTransitionRead(FSImage.java:303)
at org.apache.hadoop.hdfs.server.namenode.FSDirectory.loadFSImage(FSDirectory.java:100)
at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.initialize(FSNamesystem.java:388)
at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.<init>(FSNamesystem.java:362)
at org.apache.hadoop.hdfs.server.namenode.NameNode.initialize(NameNode.java:276)
at org.apache.hadoop.hdfs.server.namenode.NameNode.<init>(NameNode.java:496)
at org.apache.hadoop.hdfs.server.namenode.NameNode.createNameNode(NameNode.java:1279)
at org.apache.hadoop.hdfs.server.namenode.NameNode.main(NameNode.java:1288)
2012-05-31 22:04:32,705 INFO org.apache.hadoop.hdfs.server.namenode.NameNode: SHUTDOWN_MSG:
/************************************************************
SHUTDOWN_MSG: Shutting down NameNode at guxu-Lenovo-B460/127.0.1.1
************************************************************/
/************************************************************
STARTUP_MSG: Starting NameNode
STARTUP_MSG: host = guxu-Lenovo-B460/127.0.1.1
STARTUP_MSG: args = []
STARTUP_MSG: version = 1.0.3
STARTUP_MSG: build = https://svn.apache.org/repos/asf/hadoop/common/branches/branch-1.0 -r 1335192; compiled by 'hortonfo' on Tue May 8 20:31:25 UTC 2012
************************************************************/
2012-05-31 22:04:32,034 INFO org.apache.hadoop.metrics2.impl.MetricsConfig: loaded properties from hadoop-metrics2.properties
2012-05-31 22:04:32,046 INFO org.apache.hadoop.metrics2.impl.MetricsSourceAdapter: MBean for source MetricsSystem,sub=Stats registered.
2012-05-31 22:04:32,048 INFO org.apache.hadoop.metrics2.impl.MetricsSystemImpl: Scheduled snapshot period at 10 second(s).
2012-05-31 22:04:32,048 INFO org.apache.hadoop.metrics2.impl.MetricsSystemImpl: NameNode metrics system started
2012-05-31 22:04:32,237 INFO org.apache.hadoop.metrics2.impl.MetricsSourceAdapter: MBean for source ugi registered.
2012-05-31 22:04:32,242 WARN org.apache.hadoop.metrics2.impl.MetricsSystemImpl: Source name ugi already exists!
2012-05-31 22:04:32,258 INFO org.apache.hadoop.metrics2.impl.MetricsSourceAdapter: MBean for source jvm registered.
2012-05-31 22:04:32,259 INFO org.apache.hadoop.metrics2.impl.MetricsSourceAdapter: MBean for source NameNode registered.
2012-05-31 22:04:32,298 INFO org.apache.hadoop.hdfs.util.GSet: VM type = 32-bit
2012-05-31 22:04:32,298 INFO org.apache.hadoop.hdfs.util.GSet: 2% max memory = 17.77875 MB
2012-05-31 22:04:32,298 INFO org.apache.hadoop.hdfs.util.GSet: capacity = 2^22 = 4194304 entries
2012-05-31 22:04:32,298 INFO org.apache.hadoop.hdfs.util.GSet: recommended=4194304, actual=4194304
2012-05-31 22:04:32,335 INFO org.apache.hadoop.hdfs.server.namenode.FSNamesystem: fsOwner=guxu
2012-05-31 22:04:32,335 INFO org.apache.hadoop.hdfs.server.namenode.FSNamesystem: supergroup=supergroup
2012-05-31 22:04:32,335 INFO org.apache.hadoop.hdfs.server.namenode.FSNamesystem: isPermissionEnabled=true
2012-05-31 22:04:32,342 INFO org.apache.hadoop.hdfs.server.namenode.FSNamesystem: dfs.block.invalidate.limit=100
2012-05-31 22:04:32,342 INFO org.apache.hadoop.hdfs.server.namenode.FSNamesystem: isAccessTokenEnabled=false accessKeyUpdateInterval=0 min(s), accessTokenLifetime=0 min(s)
2012-05-31 22:04:32,674 INFO org.apache.hadoop.hdfs.server.namenode.FSNamesystem: Registered FSNamesystemStateMBean and NameNodeMXBean
2012-05-31 22:04:32,695 INFO org.apache.hadoop.hdfs.server.namenode.NameNode: Caching file names occuring more than 10 times
2012-05-31 22:04:32,700 INFO org.apache.hadoop.hdfs.server.common.Storage: Storage directory /home/guxu/hadoop_tmp_dir/dfs/name does not exist.
2012-05-31 22:04:32,702 ERROR org.apache.hadoop.hdfs.server.namenode.FSNamesystem: FSNamesystem initialization failed.
org.apache.hadoop.hdfs.server.common.InconsistentFSStateException: Directory /home/guxu/hadoop_tmp_dir/dfs/name is in an inconsistent state: storage directory does not exist or is not accessible.
at org.apache.hadoop.hdfs.server.namenode.FSImage.recoverTransitionRead(FSImage.java:303)
at org.apache.hadoop.hdfs.server.namenode.FSDirectory.loadFSImage(FSDirectory.java:100)
at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.initialize(FSNamesystem.java:388)
at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.<init>(FSNamesystem.java:362)
at org.apache.hadoop.hdfs.server.namenode.NameNode.initialize(NameNode.java:276)
at org.apache.hadoop.hdfs.server.namenode.NameNode.<init>(NameNode.java:496)
at org.apache.hadoop.hdfs.server.namenode.NameNode.createNameNode(NameNode.java:1279)
at org.apache.hadoop.hdfs.server.namenode.NameNode.main(NameNode.java:1288)
2012-05-31 22:04:32,704 ERROR org.apache.hadoop.hdfs.server.namenode.NameNode: org.apache.hadoop.hdfs.server.common.InconsistentFSStateException: Directory /home/guxu/hadoop_tmp_dir/dfs/name is in an inconsistent state: storage directory does not exist or is not accessible.
at org.apache.hadoop.hdfs.server.namenode.FSImage.recoverTransitionRead(FSImage.java:303)
at org.apache.hadoop.hdfs.server.namenode.FSDirectory.loadFSImage(FSDirectory.java:100)
at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.initialize(FSNamesystem.java:388)
at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.<init>(FSNamesystem.java:362)
at org.apache.hadoop.hdfs.server.namenode.NameNode.initialize(NameNode.java:276)
at org.apache.hadoop.hdfs.server.namenode.NameNode.<init>(NameNode.java:496)
at org.apache.hadoop.hdfs.server.namenode.NameNode.createNameNode(NameNode.java:1279)
at org.apache.hadoop.hdfs.server.namenode.NameNode.main(NameNode.java:1288)
2012-05-31 22:04:32,705 INFO org.apache.hadoop.hdfs.server.namenode.NameNode: SHUTDOWN_MSG:
/************************************************************
SHUTDOWN_MSG: Shutting down NameNode at guxu-Lenovo-B460/127.0.1.1
************************************************************/
注：先前我在配置hadoop时，将conf/core-site.xml里的hadoop.tmp.dir的value设为/home/guxu/hadoop_tmp_dir，然后format了。
现在将conf/core-site.xml里的hadoop.tmp.dir改为 /tmp/hadoop-guxu/dfs/name，
再次执行hadoop namenode -format。
输出如下：
12/06/09 11:07:33 INFO namenode.NameNode: STARTUP_MSG:
/************************************************************
STARTUP_MSG: Starting NameNode
STARTUP_MSG: host = guxu-Lenovo-B460/127.0.1.1
STARTUP_MSG: args = [-format]
STARTUP_MSG: version = 1.0.3
STARTUP_MSG: build = https://svn.apache.org/repos/asf/hadoop/common/branches/branch-1.0 -r 1335192; compiled by 'hortonfo' on Tue May 8 20:31:25 UTC 2012
************************************************************/
12/06/09 11:07:33 INFO util.GSet: VM type = 32-bit
12/06/09 11:07:33 INFO util.GSet: 2% max memory = 17.77875 MB
12/06/09 11:07:33 INFO util.GSet: capacity = 2^22 = 4194304 entries
12/06/09 11:07:33 INFO util.GSet: recommended=4194304, actual=4194304
12/06/09 11:07:33 INFO namenode.FSNamesystem: fsOwner=guxu
12/06/09 11:07:33 INFO namenode.FSNamesystem: supergroup=supergroup
12/06/09 11:07:33 INFO namenode.FSNamesystem: isPermissionEnabled=true
12/06/09 11:07:33 INFO namenode.FSNamesystem: dfs.block.invalidate.limit=100
12/06/09 11:07:33 INFO namenode.FSNamesystem: isAccessTokenEnabled=false accessKeyUpdateInterval=0 min(s), accessTokenLifetime=0 min(s)
12/06/09 11:07:33 INFO namenode.NameNode: Caching file names occuring more than 10 times
12/06/09 11:07:34 INFO common.Storage: Image file of size 110 saved in 0 seconds.
12/06/09 11:07:34 INFO common.Storage: Storage directory /tmp/hadoop-guxu/dfs/name/dfs/name has been successfully formatted.
12/06/09 11:07:34 INFO namenode.NameNode: SHUTDOWN_MSG:
/************************************************************
SHUTDOWN_MSG: Shutting down NameNode at guxu-Lenovo-B460/127.0.1.1
************************************************************/
/************************************************************
STARTUP_MSG: Starting NameNode
STARTUP_MSG: host = guxu-Lenovo-B460/127.0.1.1
STARTUP_MSG: args = [-format]
STARTUP_MSG: version = 1.0.3
STARTUP_MSG: build = https://svn.apache.org/repos/asf/hadoop/common/branches/branch-1.0 -r 1335192; compiled by 'hortonfo' on Tue May 8 20:31:25 UTC 2012
************************************************************/
12/06/09 11:07:33 INFO util.GSet: VM type = 32-bit
12/06/09 11:07:33 INFO util.GSet: 2% max memory = 17.77875 MB
12/06/09 11:07:33 INFO util.GSet: capacity = 2^22 = 4194304 entries
12/06/09 11:07:33 INFO util.GSet: recommended=4194304, actual=4194304
12/06/09 11:07:33 INFO namenode.FSNamesystem: fsOwner=guxu
12/06/09 11:07:33 INFO namenode.FSNamesystem: supergroup=supergroup
12/06/09 11:07:33 INFO namenode.FSNamesystem: isPermissionEnabled=true
12/06/09 11:07:33 INFO namenode.FSNamesystem: dfs.block.invalidate.limit=100
12/06/09 11:07:33 INFO namenode.FSNamesystem: isAccessTokenEnabled=false accessKeyUpdateInterval=0 min(s), accessTokenLifetime=0 min(s)
12/06/09 11:07:33 INFO namenode.NameNode: Caching file names occuring more than 10 times
12/06/09 11:07:34 INFO common.Storage: Image file of size 110 saved in 0 seconds.
12/06/09 11:07:34 INFO common.Storage: Storage directory /tmp/hadoop-guxu/dfs/name/dfs/name has been successfully formatted.
12/06/09 11:07:34 INFO namenode.NameNode: SHUTDOWN_MSG:
/************************************************************
SHUTDOWN_MSG: Shutting down NameNode at guxu-Lenovo-B460/127.0.1.1
************************************************************/
问题
在执行 ./start-all.sh时，
namenode的日志（）输出如下错误
2012-06-09 10:27:02,534
ERROR org.apache.hadoop.security.UserGroupInformation: PriviledgedActionException as:guxu cause:java.io.IOException: File /tmp/hadoop-guxu/dfs/name/mapred/system/jobtracker.info could only be replicated to 0 nodes, instead of 1
2012-06-09 10:27:02,537 INFO org.apache.hadoop.ipc.Server: IPC Server handler 5 on 9000, call addBlock(/tmp/hadoop-guxu/dfs/name/mapred/system/jobtracker.info, DFSClient_1766397871, null) from 192.168.0.105:45917: error: java.io.IOException: File /tmp/hadoop-guxu/dfs/name/mapred/system/jobtracker.info could only be replicated to 0 nodes, instead of 1
java.io.IOException: File /tmp/hadoop-guxu/dfs/name/mapred/system/jobtracker.info could only be replicated to 0 nodes, instead of 1
at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.getAdditionalBlock(FSNamesystem.java:1558)
at org.apache.hadoop.hdfs.server.namenode.NameNode.addBlock(NameNode.java:696)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.apache.hadoop.ipc.RPC$Server.call(RPC.java:563)
at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:1388)
at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:1384)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:396)
at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1121)
at org.apache.hadoop.ipc.Server$Handler.run(Server.java:1382)
2012-06-09 10:27:02,537 INFO org.apache.hadoop.ipc.Server: IPC Server handler 5 on 9000, call addBlock(/tmp/hadoop-guxu/dfs/name/mapred/system/jobtracker.info, DFSClient_1766397871, null) from 192.168.0.105:45917: error: java.io.IOException: File /tmp/hadoop-guxu/dfs/name/mapred/system/jobtracker.info could only be replicated to 0 nodes, instead of 1
java.io.IOException: File /tmp/hadoop-guxu/dfs/name/mapred/system/jobtracker.info could only be replicated to 0 nodes, instead of 1
at org.apache.hadoop.hdfs.server.namenode.FSNamesystem.getAdditionalBlock(FSNamesystem.java:1558)
at org.apache.hadoop.hdfs.server.namenode.NameNode.addBlock(NameNode.java:696)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.apache.hadoop.ipc.RPC$Server.call(RPC.java:563)
at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:1388)
at org.apache.hadoop.ipc.Server$Handler$1.run(Server.java:1384)
at java.security.AccessController.doPrivileged(Native Method)
at javax.security.auth.Subject.doAs(Subject.java:396)
at org.apache.hadoop.security.UserGroupInformation.doAs(UserGroupInformation.java:1121)
at org.apache.hadoop.ipc.Server$Handler.run(Server.java:1382)
然后通过对master和slave jps，发现一切正常！
上面出现的异常是什么原因导致的呢？
a.关闭master和slave的防火墙
b.
$./hadoop dfs -ls 查看当前用户路径/user/guxu下的内容
$./hadoop dfs -ls xx_dir 查看xx_dir路径下文件
$./hadoop dfs -cat xx_file 查看文件内容
$./hadoop dfs -mkdir newDIr 在hdfs中新建一个目录
Q：output能否多次建？
7.测试hellowrold
//在hdfs中建立一个input目录
$ hadoop fs -mkdir hello_input
$ hadoop dfs -ls
Found 1 items
drwxr-xr-x - guxu supergroup 0 2012-06-09 19:17 /user/guxu/hello_input
//删除hdfs中已有的目录（如hello_input）
$ hadoop dfs -rmr /user/guxu/hello_input
Deleted hdfs://192.168.0.105:9000/user/guxu/hello_input
hdfs里面文件的路径与linux文件路径是两套系统。
//将file0*拷贝到hdfs中
hadoop dfs -copyFromLocal /home/guxu/JavaLib/hadoop/test/hellowrold/file0* hello_input
//运行
$hadoop jar hadoop-examples-1.0.3.jar wordcount hello_input hello_output
//查看文件内容
$./hadoop dfs -cat xx_file
web管理
namenode：http://guxu-lenovo-b460:50070/dfshealth.jsp
map reduce：http://guxu-lenovo-b460:50030/jobtracker.jsp
参考
http://www.infoq.com/cn/articles/hadoop-config-tip