Hierarchical use of heterogeneous flash memories for high performance and durability
Sanghyuk Jung, Yong Ho Song · IEEE Transactions on Consumer Electronics · 2009
The use of NAND flash memory for building permanent storage has been increasing in many embedded systems due to idiosyncrasies such as non-volatility and low energy consumption. The persistent requirements for high storage capacity have given rise to the increase of bit density per cell as in multi-level cells but this has come at the expense of performance and has resulted in degradation of durability. In this paper, we introduce a complementary approach to boost the performance and durability of MLC-based storage systems by employing a non-volatile buffer that temporarily holds the data heading to MLCs. We also propose algorithms to efficiently eliminate unnecessary write and erase operations in MLCs by performing a pre-merge in the buffer. Our experiments show that the proposed approach can decrease average response time by up to 4 times and increase durability by 4 times by adding only a small hardware cost.