How to reduce the energy consumption of storage sub-system effectively has gained a lot of attention these years. The emergence of non-volatile, shock resistant and low power flash memory and solid state driver (SSD) brings a new opportunity for power-saving in storage sub-system. However, it still cannot totally replace hard disk for its higher cost per storage unit. This paper focuses on the heterogeneous drive scheme (heter-Drive for short) for both energy-conservation. By considering both file access frequencies and energy cost, we propose an improved file cache replacement scheme called FEBR (Frequency and Energy-based Replacement). We collected four real-world office users' file access data for experiments. The results show that heter-Drive does works well and saves as high as 70% ~ 80% of energy; the extensive comparisons with the classic replacement algorithms, the widely used ARC and the optimal algorithm OPT show that FEBR is consistently better than other alternatives.