Categories: Big Data

Big Data – How Data is Retrieved and Written from/to HDFS?

This blog represents my notes on how data is read and written from/to HDFS. Please feel free to suggest if it is done otherwise.

Following are steps using which clients retrieve data from HDFS:

  1. Clients ask Namenode for a file/data block
  2. Name-node returns data node information (ID) where the file/data blocks are located
  3. Client retrieves data directly from the data node.

Following are steps in which data is written to HDFS:

  1. Clients ask Name-node that they want to write one or more data blocks pertaining to a file.
  2. Name-node returns data nodes information to which these data blocks needs to be written
  3. Clients write each data block to the data nodes suggested.
  4. The data nodes then replicates the data block to other data nodes
  5. Informs Namenode about the write.
  6. Name-node commits EditLog

Following diagrams represents the data is read/written from/to HDFS.

 

 

 

 

 

 

 

 

 

 

 

Following depicts how files are written to HDFS.

Ajitesh Kumar

I have been recently working in the area of Data analytics including Data Science and Machine Learning / Deep Learning. I am also passionate about different technologies including programming languages such as Java/JEE, Javascript, Python, R, Julia, etc, and technologies such as Blockchain, mobile computing, cloud-native technologies, application security, cloud computing platforms, big data, etc. I would love to connect with you on Linkedin. Check out my latest book titled as First Principles Thinking: Building winning products using first principles thinking.

Recent Posts

Agentic Reasoning Design Patterns in AI: Examples

In recent years, artificial intelligence (AI) has evolved to include more sophisticated and capable agents,…

1 month ago

LLMs for Adaptive Learning & Personalized Education

Adaptive learning helps in tailoring learning experiences to fit the unique needs of each student.…

1 month ago

Sparse Mixture of Experts (MoE) Models: Examples

With the increasing demand for more powerful machine learning (ML) systems that can handle diverse…

2 months ago

Anxiety Disorder Detection & Machine Learning Techniques

Anxiety is a common mental health condition that affects millions of people around the world.…

2 months ago

Confounder Features & Machine Learning Models: Examples

In machine learning, confounder features or variables can significantly affect the accuracy and validity of…

2 months ago

Credit Card Fraud Detection & Machine Learning

Last updated: 26 Sept, 2024 Credit card fraud detection is a major concern for credit…

2 months ago