Comment by marcosdumay

> The # of businesses that are actually sensitive to >1 minute of annual downtime are already running on top of IBM mainframes and have been for decades.

Is there any?

My bank certainly has way less than 5 9s of availability. It's not a problem at all. Credit/debit card processors seem to stay around 5 nines, and nobody is losing sleep over it. As long as your unavailability isn't all on the Christmas promotion day, I never saw anybody losing any sleep over web-store unavailability. The FED probably doesn't have 5 9's of availability. It's way overkill for a central bank, even if it's one that process online interbank transfers (what the FED doesn't).

The organizations that need more than 5 9's are probably all on the military and science sectors. And those aren't using mainframes, they certainly use good old redundancy of equipment with simple failure modes.