Please bear with the lack of details, as my (very limited) VMS experience involved an offline system which never broke, but: it is amazingly tolerant of hardware failures, I recall sitting slack-jawed over the AlphaStation manual after learning you could hot-swap just about anything - including CPU boards!

Granted, that is as much (if not more!) a feature of the hardware architecture than the OS - but amazing still.

I've never heard of an NT box capable of that - maybe the Alpha port could do it? Anyone know?