Explain N+1 redundancy and its purpose.

Explain N+1 redundancy and its purpose.

• A. An approach where two extra components are added beyond minimum.
• B. An extra one component beyond the minimum required to tolerate a single failure without service interruption.
• C. A system with no redundancy that relies on rapid repair.
• D. Redundancy that requires manual switchover.

Answer: (B)

N+1 redundancy means you design with exactly one spare unit beyond what you need for normal operation. The baseline is N active components that meet demand, and the extra unit sits ready to take over if any one component fails. The purpose is to keep the system running without interruption when a single part fails, and it also allows maintenance or upgrades to be performed without bringing the whole system down. This spare is intended to be available immediately, so the transition happens with minimal or no downtime. The exact method of switching can be automatic or manual, but the defining idea is having that one extra component ready to cover a single failure rather than having no extra capacity at all. Other options describe different approaches: adding two extras would be an N+2 setup, which increases cost for higher availability. A system with no redundancy relies on rapid repair rather than spare capacity. Requiring manual switchover isn’t the defining feature of N+1, since many N+1 designs support automatic failover for quicker uptime.

N+1 redundancy means you design with exactly one spare unit beyond what you need for normal operation. The baseline is N active components that meet demand, and the extra unit sits ready to take over if any one component fails. The purpose is to keep the system running without interruption when a single part fails, and it also allows maintenance or upgrades to be performed without bringing the whole system down.

This spare is intended to be available immediately, so the transition happens with minimal or no downtime. The exact method of switching can be automatic or manual, but the defining idea is having that one extra component ready to cover a single failure rather than having no extra capacity at all.

Other options describe different approaches: adding two extras would be an N+2 setup, which increases cost for higher availability. A system with no redundancy relies on rapid repair rather than spare capacity. Requiring manual switchover isn’t the defining feature of N+1, since many N+1 designs support automatic failover for quicker uptime.