Split-by in Sqoop specifies the database column to be used for splitting the data during import. This is particularly useful when dealing with large datasets, allowing for parallel processing and efficient data import.

In Kerberos-based authentication for Hadoop, the krb5.conf file is crucial. It defines the realms, KDCs (Key Distribution Centers), and other configuration parameters necessary for secure authentication and authorization in a Hadoop cluster.

In capacity planning, the Throughput of hardware components is a key factor. Throughput measures the amount of data that can be processed in a given time, and it influences the overall performance of a Hadoop cluster. Ensuring sufficient throughput is essential for meeting performance requirements.

Data partitioning in Hadoop increases parallelism by distributing data across nodes. This enhances the efficiency of data transformation processes as multiple nodes can work on different partitions concurrently, speeding up overall processing.

To handle a very large input file efficiently, configuring the MapReduce job to adjust block size is crucial. Larger block sizes can lead to more efficient processing by reducing the number of input splits and overhead associated with task startup.

Kerberos in Hadoop primarily plays the role of authentication. It ensures that only legitimate users and services can access the Hadoop cluster by verifying their identities through a secure authentication process.

Parquet is the preferred file format for large-scale data processing in Hadoop due to its columnar storage, compression techniques, and schema evolution support. It offers high performance for analytical queries and is well-suited for data warehouse applications.

Hadoop clusters use Block Replication to optimize data storage and access. Data is replicated across multiple nodes to ensure data availability and fault tolerance, allowing for efficient data retrieval and processing.

To optimize data processing, Hash partitioning in Hadoop can significantly improve the performance of MapReduce jobs. Hash partitioning ensures that related data is grouped together, reducing the amount of data shuffled between nodes during the MapReduce process and improving overall performance.

Sqoop achieves high throughput in data transfer using the Direct Mode, which allows direct communication between the Sqoop client and the database, bypassing the need for intermediate storage in Hadoop. This results in faster data transfers with reduced latency.