The drift the BMS averaged away.
BMS averaged it away. Rack intake didn’t.
BMS reports room-level average temperature as clean. DCIM polls every 5 minutes — also fine. But CRAH-7’s supply temperature has been climbing 2.1°C above baseline for 45 minutes across three 15-minute windows. The ML inference racks it primarily cools are creeping into ASHRAE A1 upper. Tenant SLA penalty: $14K per hour if the envelope is breached.
Root cause: chiller rebalance left one CRAH under-fed.
Cooling pillar correlates CRAH-7’s supply drift against the chiller plant load-balance log. Root cause: a plant rebalance at 04:12 left CRAH-7 under-fed. Intervention runbook attached: two valve adjustments, estimated 10 minutes to execute. Forecast envelope remains inside ASHRAE A1 if corrected within 20 minutes.
Corrected in 6 minutes. Tenant never notices.
Operator approves the runbook. Valve adjustments executed. CRAH-7 returns to baseline within 6 minutes. Two ML inference racks never exceed the A1 envelope. EN 50600 operations log entry sealed automatically. Q3 facility report adds one more entry to the “caught and resolved before tenant exposure” column.