In Hadoop, the NameNode is responsible for storing metadata about files and directories in HDFS. It keeps track of the location and health of data blocks, playing a crucial role in the overall architecture of Hadoop's distributed file system.

When addressing 'Garbage Collection' issues in Java-based Hadoop applications, adjusting the Heap size parameter is a key strategy. Garbage Collection is the process of automatically reclaiming memory occupied by objects that are no longer in use, and adjusting the Heap size helps optimize memory management in Hadoop applications.

The advantage of using PySpark is simplified development. Python is known for its simplicity and readability, making it easier for developers to write and maintain code, resulting in increased productivity in comparison to the complexities of conventional MapReduce jobs.

The primary role of Apache Hive in the Hadoop ecosystem is data querying. Hive provides a SQL-like language called HiveQL that allows users to query and analyze data stored in Hadoop. It translates HiveQL queries into MapReduce jobs, making it easier for users familiar with SQL to work with big data.

Apache Spark employs in-memory processing for efficient data transformation. It keeps intermediate data in memory, reducing the need to write to disk and significantly speeding up processing compared to traditional batch processing.

Data locality in MapReduce is achieved through node proximity. The framework schedules tasks to nodes where the data is already stored, minimizing data transfer over the network. This strategy enhances performance by reducing data movement and leveraging the proximity of computation and data.

When processing time-sensitive data, increasing Speculative Execution in the job configuration can help achieve timely execution. Speculative Execution involves running duplicate tasks on other nodes to finish faster, reducing the impact of slow-running tasks on job completion time.

Write-Ahead Logging (WAL) in Hadoop ensures data integrity during massive data ingestion. It records changes before they are applied, allowing recovery in case of system failure during the ingestion process.

In the context of periodic data analysis jobs, the Oozie component ensuring timely execution is the Bundle. Bundles provide a higher-level abstraction for managing and scheduling multiple coordinators. They allow you to group and coordinate multiple jobs, making them suitable for use cases involving periodic and interdependent data analysis tasks.

MRUnit is most commonly used for Unit Testing in the Hadoop ecosystem. It provides a framework for writing and running unit tests for MapReduce jobs, allowing developers to validate the correctness of their code in a controlled environment.