One or more operating conditions of an LED device is sensed, and the sensed condition is communicated to an LED driver by modulating a load thereof. The multi-layer-information-recording medium is compatible in terms of at least reproducing and recording with a single-layer-information-recording medium having a cover layer having a predetermined refractive index n and a thickness t disposed on a recording layer on a light incident side surface. Dynamic server power management and optional dynamic workload management for multi-server environments is provided by aspects of the invention. Zero insertion may be automatically generated in the LFSRs without additional mask circuitry.