七，启动Hadoop
1， 启动hadoop日志报错
./start-all.sh
WARN org.apache.hadoop.hdfs.DFSClient: DataStreamerException: org.apache.hadoop.ipc.RemoteException: java.io.IOException: File/tmp/hadoop/mapred/system/jobtracker.info could only be replicated to 0 nodes,instead of 1
解决方法：关闭hadoop安全模式：hadoop dfsadmin -safemode leave（此时并未关闭hadoop）。
等待一会，hadoop自动恢复成功。
观察日志hadoop-root-jobtracker-da-free-test1.log，可以看到：
2012-02-08 12:14:07,804 INFOorg.apache.hadoop.ipc.Server: IPC Server Responder: starting
2012-02-08 12:14:07,804 INFOorg.apache.hadoop.ipc.Server: IPC Server listener on 9001: starting
2012-02-08 12:14:07,805 INFOorg.apache.hadoop.ipc.Server: IPC Server handler 0 on 9001: starting
2012-02-08 12:14:07,805 INFOorg.apache.hadoop.ipc.Server: IPC Server handler 1 on 9001: starting
2012-02-08 12:14:07,805 INFOorg.apache.hadoop.ipc.Server: IPC Server handler 2 on 9001: starting
2012-02-08 12:14:07,805 INFO org.apache.hadoop.ipc.Server:IPC Server handler 3 on 9001: starting
2012-02-08 12:14:07,805 INFOorg.apache.hadoop.ipc.Server: IPC Server handler 4 on 9001: starting
2012-02-08 12:14:07,805 INFOorg.apache.hadoop.ipc.Server: IPC Server handler 5 on 9001: starting
2012-02-08 12:14:07,806 INFOorg.apache.hadoop.ipc.Server: IPC Server handler 6 on 9001: starting
2012-02-08 12:14:07,806 INFOorg.apache.hadoop.ipc.Server: IPC Server handler 7 on 9001: starting
2012-02-08 12:14:07,806 INFOorg.apache.hadoop.ipc.Server: IPC Server handler 8 on 9001: starting
2012-02-08 12:14:07,806 INFOorg.apache.hadoop.ipc.Server: IPC Server handler 9 on 9001: starting
2012-02-08 12:14:07,806 INFOorg.apache.hadoop.ipc.Server: IPC Server handler 10 on 9001: starting
2012-02-08 12:14:07,806 INFOorg.apache.hadoop.ipc.Server: IPC Server handler 11 on 9001: starting
2012-02-08 12:14:07,806 INFOorg.apache.hadoop.ipc.Server: IPC Server handler 12 on 9001: starting
2012-02-08 12:14:07,806 INFOorg.apache.hadoop.ipc.Server: IPC Server handler 13 on 9001: starting
2012-02-08 12:14:07,806 INFOorg.apache.hadoop.ipc.Server: IPC Server handler 14 on 9001: starting
2012-02-08 12:14:07,807 INFOorg.apache.hadoop.ipc.Server: IPC Server handler 15 on 9001: starting
2012-02-08 12:14:07,807 INFO org.apache.hadoop.ipc.Server:IPC Server handler 16 on 9001: starting
2012-02-08 12:14:07,807 INFOorg.apache.hadoop.ipc.Server: IPC Server handler 17 on 9001: starting
2012-02-08 12:14:07,807 INFOorg.apache.hadoop.ipc.Server: IPC Server handler 18 on 9001: starting
2012-02-08 12:14:07,807 INFOorg.apache.hadoop.ipc.Server: IPC Server handler 19 on 9001: starting
2012-02-08 12:14:07,807 INFOorg.apache.hadoop.ipc.Server: IPC Server handler 20 on 9001: starting
2012-02-08 12:14:07,807 INFOorg.apache.hadoop.ipc.Server: IPC Server handler 21 on 9001: starting
2012-02-08 12:14:07,807 INFOorg.apache.hadoop.ipc.Server: IPC Server handler 22 on 9001: starting
2012-02-08 12:14:07,808 INFOorg.apache.hadoop.ipc.Server: IPC Server handler 23 on 9001: starting
2012-02-08 12:14:07,808 INFOorg.apache.hadoop.ipc.Server: IPC Server handler 25 on 9001: starting
2012-02-08 12:14:07,808 INFOorg.apache.hadoop.ipc.Server: IPC Server handler 26 on 9001: starting
2012-02-08 12:14:07,808 INFOorg.apache.hadoop.ipc.Server: IPC Server handler 27 on 9001: starting
2012-02-08 12:14:07,808 INFOorg.apache.hadoop.ipc.Server: IPC Server handler 28 on 9001: starting
2012-02-08 12:14:07,808 INFOorg.apache.hadoop.mapred.JobTracker: Starting RUNNING
2012-02-08 12:14:07,808 INFO org.apache.hadoop.ipc.Server:IPC Server handler 29 on 9001: starting
2012-02-08 12:14:07,808 INFOorg.apache.hadoop.ipc.Server: IPC Server handler 24 on 9001: starting
2012-02-08 12:14:12,623 INFOorg.apache.hadoop.net.NetworkTopology: Adding a new node: /default-rack/da-free-test4
2012-02-08 12:14:12,625 INFOorg.apache.hadoop.mapred.JobTracker: Adding trackertracker_da-free-test4:da-free-test1/127.0.0.1:42182 to host da-free-test4
2012-02-08 12:14:12,743 INFOorg.apache.hadoop.net.NetworkTopology: Adding a new node:/default-rack/da-free-test3
2012-02-08 12:14:12,744 INFOorg.apache.hadoop.mapred.JobTracker: Adding trackertracker_da-free-test3:da-free-test1/127.0.0.1:53695 to host da-free-test3
2012-02-08 12:14:12,802 INFOorg.apache.hadoop.net.NetworkTopology: Adding a new node:/default-rack/da-free-test2
2012-02-08 12:14:12,802 INFOorg.apache.hadoop.mapred.JobTracker: Adding trackertracker_da-free-test2:da-free-test1/127.0.0.1:47259 to host da-free-test2
打开浏览器，输入:50030，可以看到节点数量为3。
上传一个文件：dfs -put hadoop-root-namenode-da-free-test1.log /usr/testfile
查看上传的文件：hadoop dfs -ls /usr/
Found 1 items
-rw-r--r-- 3 root supergroup 845332012-02-08 12:20 /usr/testfile
查看:50070，发现已用空间为396k。
暂时验证通过。
