Focus System design on Hardware scalability rather than on capacity

Adding More hardware leads quickly to diminishing results. Yes, In some cases the problem can be resolved with additional hardware, but not all the times adding more hardware leads quickly to diminishing returns.


For example: 
Suppose we can improve 70% of a module by parallelizing it, and run on 4 cpus instead of 1 cpu. 
If a is the fraction of a calculation that is sequential, and (1-a) is the fraction that can be parallelized, then the maximun speedup that can be achieved by using P processors is given according to Amdahl's law: 1/[a+{(1-a)}/p]


in this example we would get: 1/[.3+(1-3)/4] = 2.105. so for quadrupling the processing power we only doubled the performance from (1 to 2.105). and we are now
well on the way to diminishing returns. If we go on to double the computing power again from 4 to 8 processors we get 1/[.3+(1-.3)/8] = 2.581. so, now by doubling the processing power again we only got a performance improvement of about one fifth (from 2.105 to 2.581).