Massively Parallel System
Refers to a parallel computer system having a great number of processors. The number in a great number of keeps increasing and currently it means more than 1000.
Scalability
Refers to a parallel system's (software/hardware) ability to exhibit a proportionate increase in (parallel) accelerate with the addition of more processors. Features that contribute to scalability include:
Hardware - particularly memory- Network communications and CPU bandwidths:
- Parallel overhead related
- Application algorithm
- Characteristics of your coding and specific application