Understanding HDFS Architecture: NameNode, DataNode, Replication, and Block Storage
Definition
HDFS (Hadoop Distributed File System) is a distributed file system designed to run on commodity hardware. It is highly fault-tolerant and is designed store large files across multiple machines.
: Imagine you have a large video file that you want to store. Instead of saving it on a single, HDFS splits it into smaller chunks (blocks) saves blocks across several computers (nodes) to ensure reliability and availability.
Explanation
Key Components of H
1.Node- **Definition The NameNode is the master server that manages the metadata the file system. It keeps track the structure of the file system and the location each block of data.
ality: -ains the directory tree of all files in the system.
- the locations of data blocks on DataNodes.
- Responsible for system operations like opening, closing, and renaming files.
**Real-World Example In a university, the NameNode acts like the registrar office, which knows where student's records (files) are stored different departments (DataNodes).
2 DataNode
Definition: DataNodes the worker nodes store actual data blocks. They are responsible for serving read and requests from the clients.
- Functionality:
- Stores data blocks and serves them when requested.
- Regularly sends heartbeat signals to the NameNode to confirm that it is functioning properly.
- block replication as per the from the NameNode.
Real-World Example: Think ofNodes as the filing cabinets various of a university where cabinet holds the actual student records.
3. Data Replication
-Definition:** Data replication is the process storing copies of data blocks multiple DataNodes to ensure reliability and availability.
- Functionality:
- By default HDFS replicates each three times across different DataNodes.
- If one DataNode, the system can still access the data from another DataNode that has a copy.
Real-World Example:** like a library multiple copies of books different locations to ensure that they are always available readers.
4. Block
- **Definition:**DFS divides files into fixed-size blocks (default 128 MB