The document summarizes key components of Hadoop including: 1) The NameNode, located on the master node, stores metadata for HDFS such as file locations and attributes. 2) DataNodes, located on slave nodes, store and retrieve data blocks. 3) The JobTracker, located on the master node, schedules jobs and assigns tasks to TaskTrackers on slave nodes.

1. Hadoop
Edit by Cassell Hsu
2013.04.19

2. Hadoop
Master
Slave
Slave
Slave

3. Hadoop
• Master
• NameNode
• JobTracker
• SecondaryNameNode

4. NameNode
• Where is NameNode?
• Master
• HDFS(Hadoop Distributed File
System)
• What is NameNode?
• 資料之位置資訊
• 資料之屬性
？？

5. NameNode
• 位置資訊?
• 所有資料皆存放在 – DataNode

6. DataNode
• What is DataNode
• 存放資料
• Where is DataNode
• HDFS
• Slaves (and Master)

7. User
DataNode
NameNode
DataNode
DataNode
128
Mb B
64Mb
A
64Mb
Check hdfs-site.xml
B
64Mb
A
64Mb

8. Hadoop
DataNodeNameNode
Master
DataNode
DataNode
DataNode
Slaves

9. Hadoop
• Master
• NameNode
• JobTracker
• SecondaryNameNode

10. JobTracker
• What is JobTracker?
• 排程工作
• Where is JobTracker?
• Master
誰來工作？

11. JobTracker &
TaskTrackerJobTracker TaskTracker
Where Master Slaves
What 排程工作 執行工作

12. Hadoop
DataNodeNameNode
Master
DataNode
Slaves
JobTracker
TaskTracker

13. Hadoop
• Master
• NameNode
• JobTracker
• SecondaryNameNode

14. SecondaryNameNo
de
• What is SecondaryNameNode?
• NameNode發生錯誤時補救
• Where is SecondaryNameNode?
• Master

15. Hadoop
DataNodeNameNode
Master
DataNode
Slaves
JobTracker
TaskTracker
SecondaryNode

16. MapReduce
User Maste
r
Slave
2
Slave1
A
A1
A2
Task
NameNod
e
Task
Resul
t1
Resul
t2
Reduc
e
Final
Result
HDFS

17. MapReduce
• 檔案切割
• Hadoop上區塊切割
• 程式指定