Hope you are doing great.
Tuning of a Cluster : it is a General Process to maintain the Cluster in very good condition.
Performance tuning is the improvement of system performance. This is typically a computer systems. The motivation for such activity is called a performance problem, which can be real or anticipated.
Most systems will respond to increased load with some degree of decreasing performance. A system's ability to accept higher load is called scalability, and modifying a system to handle a higher load is synonymous to performance tuning.
I have also attached a sample document for your reference.