Controls overall QoS processing for the system. When enabled, all QoS functionality can be exercised by the user. When disabled, installed QoS components are temporarily removed (until the operational mode is re-enabled) and new requested QoS operations will be rejected. The QoS operational mode can not be disabled if QoS components are currently being used by non-QoS applications. If disabled, requests related to QoS components by non-QoS applications will be rejected. Note that re-enabling the QoS operational mode may result in errors if changes have been made affecting available resources while QoS was temporarily disabled. Mode changes (updates to the value of this attribute) will take effect immediately.