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Flash memory has many attractive features such as small size, low-power consumption, shock resistance, and high performance. Due to these good features, flash memory has been widely used in the mobile consumer devices such as portable media players (PMPs) and smart phones. However, the cost of flash memory is still high to accommodate ever-growing mobile applications and multimedia contents. Using flash memory and mobile disk together as secondary storage is an alternative solution to provide large storage capacity with reasonable cost. As heterogeneous storage devices are used together, the system needs a buffer management policy that is aware of different I/O characteristics of buffered blocks depending on which devices they belong to. Specifically, power consumption rate of each storage device should be considered in the design of an efficient buffer management policy since battery limitation of mobile systems is important. This paper presents a new buffer management policy for mobile systems consisting of heterogeneous storage devices such as flash memory and mobile disk. By considering different power-consumption rates of each storage media as well as I/O operation type and reference potential of buffered blocks, the proposed policy reduces storage power consumption significantly and also improves I/O performances.
Date of Publication: November 2010