Abstract: Recent technological advancements have enabled a generation of Ultra-Low Latency (ULL) SSDs that blurs the performance gap between primary and secondary storage devices. However, their power consumption characteristics are largely unknown. In addition, ULL performance in a block device is expected to put extra pressure on operating system components, significantly affecting energy efficiency of the entire system. In this work, we empirically study overall energy efficiency using a real ULL storage device, , a power meter, and a wide range of IO workload behaviors. We present a comparative analysis by laying out several critical observations related to idle vs. active behavior, read vs. write behavior, energy proportionality, impact on system software, as well as impact on overall energy efficiency. To the best of our knowledge, this is the first published study of a ULL SSD's impact on the system's overall power consumption, which can hopefully lead to future energy-efficient designs.