Much attention has been paid to low-power design due to the popularity of laptops and other portable electronic devices. However, previous research has generally focused on low-power hardware components. Little work has been done to determine ways of reducing disk drive power consumption using only software. This thesis addresses one way: arranging disk data to minimize disk drive power consumption. Our measurements show that shorter seek distances consume less energy. Combined with the trace colleciton method and the System Assisted Disk I/O Simulation Technique (SAST) developed by the Performance Evaluation Laboratory (PEL) of the Computer Science Depoartment of Brigham Young University, our algorithm could allow researchers to determine and quantify both the perfromance and energy consumption impact of alternative file system designs and disk data rearrangement techniques. By accepting disk trace data as simulation input, our system can accurately predict disk energy consumption.