Massively Parallel System
Indicates to a "parallel computer system" involving a huge number of processors. The numbers in a huge number of processors keeps increasing and currently it means over 1000.
Scalability
Indicates to parallel system's (software and/or hardware) ability to exhibit a proportionate raise in (parallel) boost with the addition of additional processors. Factors which contribute to scalability involve:
Hardware
Specifically CPU-Memory bandwidths and network communications:
- Parallel overhead related
- Application algorithm
- Characteristics of your individual application and coding