No, you cannot download HDFS alone because Hadoop 2.X has four core components:
- HDFS – It is the core component of Hadoop Ecosystem which is used to store a huge amount of data.
- Map Reduce – It is used for processing of large distributed datasets parallelly.
- YARN – It is the resource manager responsible for managing resources in cluster and scheduling applications.
- Hadoop Common – It is the collection of utilities and libraries that support other Hadoop modules
Even if you want to implement a simple word count program, you need all the components, so when you install Hadoop all the three components will be installed.
To install Hadoop, visit apache.hadoop.org and download the most recent stable version.