[bowyakka]

> Is your reasonably small bank known for its reliability and fault tolerance? The main reason banks don't go offline is because the core critical infrastructure is running on 50 year old mainframes that no one is allowed to touch because all of the greybeards with actual talent who made them are pushing up daisies.

> Nowhere did I say you should be on one incredibly large server, nor that you should have a single point of failure. That wouldn't be simple, either, because it would fail to support the prime directive, or would require a great deal of gymnastics to. It's about balance. You don't need thousands of servers to make a reliable system.

Heh those things go offline every night for 2 hour maintenance.

Also fun when those nice single points of failure crash (they do)

Source: work at a shop trying to _get out of_ greybeard mainframe to get more reliablity

[AmericanChopper]

Most banks have a window of a couple of hours per night where access to the core system is restricted for settlement. It's kind of a necessity of the business model. However most banks (including every bank I've ever worked at, which is quite a few), don't shut down services during that time. ATM, credit and debit cards, everything else... All those systems run all the time. They just have an eventual consistency model. The compromise that the banks tend to make, is that certain types of fraud are more tolerated during that window, rather than sacrificing availability.