• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.1
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• pp.36-42
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• 2016

In multi-level-cell based storage devices, TLC NAND has been employed solid state drive due to cost effectiveness. Since TLC has slow performance and low endurance compared with MLC, TLC based storage has adopted SLC buffer scheme to improve performance. To improve SLC buffer scheme, this paper proposes page overwriting method in SLC block. This method provides data updates without erase operation within a limited number. When SLC buffer area is filled up, FTL should execute copying valid pages and erasing it. The proposed method reduces erase counts by 50% or more compared with previous SLC buffer scheme. Simulation results show that the proposed SLC buffer overwrite method achieves 2 times write performance improvement.

• Journal of the Institute of Electronics and Information Engineers
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• v.52 no.9
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• pp.54-62
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• 2015

Although NAND flash-based SSD (Solid-State Drive) provides superior performance in comparison to HDD (Hard Disk Drive), it has a major drawback in write endurance. As a result, the lifetime of SSD is determined by the workload and thus it becomes a big challenge in current technology trend of such as the shifting from SLC (Single Level Cell) to MLC (Multi Level cell) and even TLC (Triple Level Cell). Most previous studies have dealt with wear-leveling or improving SSD lifetime regarding hardware architecture. In this paper, we propose the optimal configuration of host I/O stack focusing on file system, I/O scheduler, and link power management using JEDEC enterprise workloads in terms of WAF (Write Amplification Factor) which represents the efficiency perspective of SSD life time especially for host write processing into flash memory. Experimental analysis shows that the optimum configuration of I/O stack for the perspective of SSD lifetime is MinPower-Dead-XFS which prolongs the lifetime of SSD approximately 2.6 times in comparison with MaxPower-Cfq-Ext4, the best performance combination. Though the performance was reduced by 13%, this contributions demonstrates a considerable aspect of SSD lifetime in relation to I/O stack optimization.