Distinguish between hot, warm, and cold spare philosophy and when each would be employed.

Distinguish between hot, warm, and cold spare philosophy and when each would be employed.

• A. Hot spare is active; warm spare powered but idle; cold spare powered off.
• B. All spares are always active.
• C. Spares are only used during maintenance.
• D. There is no spare concept in fault-tolerant designs.

Answer: (A)

Spare readiness levels determine how quickly a fault-tolerant system can recover after a component fails. A hot spare is active and running, ready to take over immediately with no delay. A warm spare is powered and kept in standby, ready to activate but not currently serving, which allows a fast switchover with some minimal overhead. A cold spare is powered off and must be powered up and initialized before it can take over, which takes more time but saves power and resources. This aligns with the described approach: a hot spare is active, a warm spare is powered but idle, and a cold spare is powered off. The other statements don’t fit typical fault-tolerant practice because spares aren’t usually kept all active at once, they aren’t used only during maintenance, and the spare concept is a standard part of fault-tolerant designs.

Spare readiness levels determine how quickly a fault-tolerant system can recover after a component fails. A hot spare is active and running, ready to take over immediately with no delay. A warm spare is powered and kept in standby, ready to activate but not currently serving, which allows a fast switchover with some minimal overhead. A cold spare is powered off and must be powered up and initialized before it can take over, which takes more time but saves power and resources. This aligns with the described approach: a hot spare is active, a warm spare is powered but idle, and a cold spare is powered off. The other statements don’t fit typical fault-tolerant practice because spares aren’t usually kept all active at once, they aren’t used only during maintenance, and the spare concept is a standard part of fault-tolerant designs.