Because I'm feeling pedantic today: you meant to say "a fault-tolerant system". A fail-safe system is one which fails in a safe way. An example would be a CPU that shuts itself down if it's overheating, rather than risk permanent damage. If anything, a fail-safe system may be more prone to failure because of its cautious approach to dealing with faults.

There are some pretty cool examples on the Wikipedia page:

http://en.wikipedia.org/wiki/Fail-safe