200-150 · Question #187
Which characteristic of the n+1 power redundancy mode is true?
The correct answer is C. It uses one more PSU than required to power the chassis.. N+1 redundancy provides exactly one additional PSU beyond the minimum count needed to power the chassis, so a single PSU failure is tolerated.
Question
Which characteristic of the n+1 power redundancy mode is true?
Options
- AIt uses fully redundant PSUs supplied by a single circuit.
- BIt uses fully redundant PSUs supplied by different circuits.
- CIt uses one more PSU than required to power the chassis.
- DIt uses the minimum number of PSUs required to power
How the community answered
(36 responses)- A3% (1)
- B8% (3)
- C86% (31)
- D3% (1)
Why each option
N+1 redundancy provides exactly one additional PSU beyond the minimum count needed to power the chassis, so a single PSU failure is tolerated.
Fully redundant PSUs supplied by a single circuit describes combined redundancy, which does not protect against a circuit-level or breaker failure the way N+1 protects against a single PSU failure.
Fully redundant PSUs supplied by different circuits describes grid or dual-feed redundancy, which is a higher tier of protection than N+1 and requires separate electrical feeds.
In N+1 power redundancy, N is the number of PSUs required to sustain full chassis operation, and the additional +1 PSU acts as a live standby so any single PSU failure does not affect system operation. This is distinct from full grid redundancy, which mirrors the entire power supply across two independent electrical circuits.
Using the minimum number of PSUs required to power the chassis describes a non-redundant combined power mode that provides no fault tolerance against a PSU failure.
Concept tested: N+1 power supply redundancy mode behavior
Source: https://www.cisco.com/c/en/us/td/docs/switches/datacenter/nexus7000/hw/installation/guide/n7k_hig/n7k_install_chapter3.html
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