The Right Number of Cluster Redundancy to Achieve the Availability Goal. Trubin's Law #4!

...Still playing with the availability algebra exercise, that I started in my other post:  How to Calculate Availability of Clustered Infrastructure for Multi-Tier Application

I have built the following two charts to see how the same availability goal can be achieved by different number of redundancy.

That of course possible if the less redundant configuration has more available individual components.

By the way, interesting that if the component availability has one 9's  (90.00%), then increasing redundancy on +1 gives the additional one 9's for the cluster availability. 

So, the equation

has the following solution:  A=0.9  for any integer n within the interval (0,∞)

It is probably the known law in the availability algebra. If not let's call that Trubin's law #4! ;)
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This Saga of 9's continuous in the next post:

Cluster Availability 9's Equation