Telephony central office switches are an example of the sort of systems you are asking after. A typical switch is designed to run for 30 years with less than 30

Telephony central office switches are an example of the sort of systems you are asking after. A typical switch is designed to run for 30 years with less than 30 minutes downtime in all that time. Ericsson AXE and Western Electric are two such systems I have worked with. More recent example would be the Erlang language and the related OTP environment.