The summary.
THE POWER PATH HAS MANY STAGES
Supply, switchgear, uninterruptible supplies, distribution, rack units, device supplies. A failure anywhere affects everything downstream.
Redundancy means two genuinely independent paths — check they do not share an upstream component.
THE ERROR THAT DEFEATS REDUNDANCY
Both power supplies of a server plugged into the same feed.
Trace them physically and label them, and balance load so either path can carry everything alone.
BATTERIES BRIDGE SECONDS; GENERATORS CARRY HOURS
Ask when the batteries were last tested and what runtime they give at current load. Untested batteries may give none.
Ask how often generators run under full load — one that starts but cannot carry the load has not been proven.
FUEL LOGISTICS IS THE REAL CONSTRAINT IN AN EXTENDED OUTAGE
Ask how many hours are stored, and whether the resupply arrangement has ever been exercised.
CALCULATE ACTUAL CONSUMPTION, NOT NAMEPLATE RATINGS
Those are far above typical use. Then monitor real consumption against your allocation.
EVERY WATT CONSUMED BECOMES HEAT THAT COSTS MORE ENERGY TO REMOVE
So removing unused equipment saves twice. Idle servers consume substantially for no output.
