Failure tolerance

Failure tolerance is the concept of such a system operation in which the end-user of the system cannot notice the failure of part of it from regular work. Some fault-tolerance tools and techniques are similar to high availability tools and techniques, which facilitate the provision of services by a system when a certain part of it fails while recovering the very part that suffered the failure. However, no set guarantees that any recovery will be instant and 100% complete. So "fault tolerance" is still a concept to strive for, but not an end point to be reached.