Comment by the8472
12 hours ago
I'm saying that if you have eliminated more mundane failures like dying harddrives, cosmic rays and so on from your systems and your calculation ends up with 11 nines then actually those "force majeure" events are probable enough that they dominate whatever other residuals are supposedly hiding in those last 0.0000000001%.
The region has seen a bunch of wars in the last 100 years, so the annual war-rate is > 1%. Even if we generously add the assumption that only 1 in 100 wars affects a datacenter you can see that wars become a major source of correlated hardware failures that they need to solve to actually deliver that kind of reliability.
You don’t want to blend probabilities like this, because the tactics you use as a consumer vary between the two. If you consider 11 9s like “object AFR”, you might build systems that are resilient to very occasional single object loss. And it’s useful to know at what rate that might occur.
Whereas with these force majeure events you’d want a complete DR setup, and it’s typically an async recovery. Here it is useful to understand the fault domain (single server or single building or multi-building) so you can plan.
Blending the two numbers doesn’t help you build better against the systems. And the force majeure events are rare enough that they won’t happen … until they do. I’m not sure that knowing the precise probability that Iran would attack a gulf nation would change the fact that if they do, you need to have a DR story.
Cosmic rays and dying hard drives are not force majeure though.