Two Fibre Channel directors are being installed in a rack. The rack has two power buses, each attached to a separate Power Distribution Unit (PDU). The directors have dual power supplies to supply N+1

This choice is incomplete as it does not specify how the dual power supplies of each director should be connected, potentially still allowing a single point of failure if both supplies connect to the same bus.

Connecting each director's power supplies to separate power buses (e.g., one PSU to Bus 1 and the other PSU to Bus 2) provides full redundancy. This configuration ensures that if one power bus or its associated Power Distribution Unit (PDU) fails, the director can continue to draw power from the other independent bus via its second power supply, preventing a single point of failure and maintaining high availability.

Plugging both directors into the same power bus creates a single point of failure; a failure of that specific bus would de-energize both critical directors despite their individual dual power supplies.

While proper grounding is essential for safety, this option disregards the primary purpose of dual power supplies and redundant buses, which is to provide power redundancy and high availability, making it incorrect from a resilience perspective.