ITPEC FE Morning October 2019 Question 15

Redundancy in the system configuration — a fault-tolerant system keeps processing when a part fails, which needs a spare part already in place to take over.

Fault tolerance accepts that parts will fail and designs the system so that one failure does not stop it: duplicated components, dual or duplex systems, RAID and similar. The other options deal with human error, or with recovery after the system has already stopped.

Answer (d)

Why not others:

• •(a) — logging changes (a journal) supports investigating and recovering after a failure; processing still stops
• •(b) — fool-proof design guards against human operating errors, not the failure of parts
• •(c) — backup and restore bring the system back after a failure; processing is interrupted until the restore is done

Key rule: Fault avoidance makes parts less likely to fail, fault tolerance keeps the system running when they do fail through redundancy, and backups and logs only speed recovery.

System Component · AI-written, may contain errors