Described is an IO driven, feedback based rate control mechanism that allows a transfer session to self-adjust its transfer rate in response to the speed of the storage device at the destination. The substrate has front and back surfaces on opposite sides of the substrate. In aspects, a testing tool hosted on the configuration management server can verify the correct implementation of configuration instructions. A light emission unit is formed on a surface of the second substrate facing the first substrate, and includes phosphor layers and an anode electrode.