SCORE

By You Zhou, Fei Wu, Zhonghai Lu, Xubin He, Ping Huang, Changsheng Xie. 2018

222 citations recorded by the source corpus.

Technology scaling and program/erase cycling result in an increasing bit error rate in NAND flash storage. Some solid state drives (SSDs) adopt overlong error correction codes (ECCs), whose redundancy size exceeds the spare area limit of flash pages, to protect user data for improved reliability and lifetime. However, the read performance is significantly degraded, because a logical data page and its ECC redundancy are stored in two flash pages. In this article, we find that caching ECCs has a large potential to reduce flash reads by achieving higher hit rates, compared to caching data. Then, we propose a novel scheme to efficiently cache overlong ECCs, called SCORE, to improve the SSD performance. Exceeding ECC redundancy (called ECC residues) of logically consecutive data pages are grouped into ECC pages. SCORE partitions RAM to cache both data pages and ECC pages in a workload-adaptive manner. Finally, we verify SCORE using extensive trace-driven simulations. The results show that SCORE obtains high ECC hit rates without sacrificing data hit rates, thus improving the read performance by an average of 22% under various workloads, compared to the state-of-the-art schemes.

Subfields: Computational Theory and Mathematics, Computer Networks and Communications, Evaluation & Benchmarks

Citations in the corpus