This read-only INTEGER field is the 'reservedPower' property of the 'FexPowerSummaryHist' managed object in Cisco UCS Manager's equipment-inventory schema for the FEX (Fabric Extender) subsystem representing the power set aside for this FEX from the shared pool. This is the slice of the shared power budget UCS Manager has locked in for the FEX regardless of what else draws from the same pool, so a rise here means the fabric interconnect has had to commit more power specifically to keep this FEX stable. A FEX might have 80W ReservedPower held aside even while its AvailablePower fluctuates with what else is plugged into the same power domain.