Which storage device is the greenest? Modeling the energy cost of I/O workloads

The performance requirements and amount of work of an I/O workload affect the number of storage devices and the run time needed by the workload, and should be included in the calculation of the cost or energy consumption of storage devices. This paper introduces models to calculate the cost and energy consumption of storage devices for running a variety of workloads, categorized by their dominant requirements. Measurements of two latest hard disk and solid-state drive (SSD) are included to illustrate the models in practice. Contrary to common belief, SSD is not the energy efficient choice for many workloads