juniorHadoop
What is a DataNode?
Updated May 16, 2026
Short answer
DataNode stores actual data blocks in HDFS.
Deep explanation
It handles read/write requests and reports to NameNode.
Real-world example
Each server in a Hadoop cluster acting as storage node.
Common mistakes
- Thinking DataNode stores metadata.
Follow-up questions
- What is heartbeats?
- What if DataNode fails?