[tahoe-dev] Reliability Calculator fails on long time periods?

[Garonda Rodian]

Looking at the Reliability Calculator on Jason Johnson's setup (1.9.2), and then taking all defaults except for the last one (report_span), which I set to 25Y from the default 5Y, I noticed that the probability of failure without maintenance peaks at 15 years and 7 months at about 0.628, and then starts decreasing again, which seems extremely odd.

Then changing drive lifetime to 7Y from 8Y, the peak changes to 13 years 6 months, also just over 0.628.

Then changing N to 15, the peak changes to 16 years 3 months, at 0.615

Then changing k to 4, the peak changes to 14 years 4 months, at 0.760

Going back to the defaults, except for changing k to 4, gives us a peak of 13 years 2 months, at 0.777.

Hopefully this will help track down the issue with the math (assuming it wasn't fixed in 1.10.0 - I'm still working through python basics to be able to quickly build test grids).
 		 	   		  
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