| Feature | Hadoop 1 | Hadoop 2 | Hadoop 3 |
| NameNode | Single point of failure | Multiple NameNodes, active-standby | Multiple NameNodes, active-active |
| Secondary NameNode | Not required | Required | Not required |
| JobTracker | Single point of failure | Resource Manager | Resource Manager |
| TaskTracker | Single point of failure | NodeManager | NodeManager |
| MapReduce | Only supported programming model | Supports multiple programming models, including MapReduce, Spark, and Tez | Supports multiple programming models, including MapReduce, Spark, Tez, and Beam |
| HDFS | Supports only one namespace | Supports multiple namespaces | Supports multiple namespaces |
| Scalability | Limited to 4,000 nodes | Scalable to 10,000 nodes | Scalable to more than 10,000 nodes |
| Security | Not a primary focus | Security is a primary focus | Security is a primary focus |
| Support | Limited | Extensive | Extensive |
Hadoop 3 is the latest version of Hadoop and it includes many new features and improvements over Hadoop 1 and Hadoop 2. Some of the key features of Hadoop 3 include:
- Multiple NameNodes, active-active: This provides high availability for the NameNode.
- Not requiring a Secondary NameNode: This reduces the overhead of running a Hadoop cluster.
- Multiple Resource Managers: This allows for better scalability and load balancing.
- Multiple NodeManagers: This allows for better scalability and load balancing.
- Support for multiple programming models: This makes Hadoop more versatile and allows it to be used for a wider range of applications.
- Support for multiple namespaces: This allows for better organization and management of data.
- Improved scalability: Hadoop 3 can scale to more than 10,000 nodes.
- Improved security: Hadoop 3 has a number of security enhancements, including support for Kerberos authentication.
- Extensive support: Hadoop 3 has a large and active community that provides support for users and developers.
If you are considering using Hadoop, I recommend using Hadoop 3. It is the most mature and feature-rich version of Hadoop.