A read-while-write-based out-of-order scheduling for high performance NAND flash-based storage devices

Recently, Phase-change RAMs (PRAMs) are considered to be as a good candidate that can substitute as DRAM cache buffers (CBs) in NAND flash-based storage devices (NFSDs). PRAM is an adequate device to mobile consumer electronics thanks to low static power consumption, high density and non-volatility. However, in spite of many advantages over DRAM, asymmetric write/read speed of PRAM causes performance degradation in NFSD. In this paper, hence, we first propose a novel scheduling method for an NFSD with PRAM CB utilizing read-while-write (RWW) of PRAM. The method schedules NFSD´s requests to service read and write simultaneously using RWW. In the experiment result, the proposed method reduces read and write latency on average by 30% and 19%, respectively.