Reaping Both Latency and Reliability Benefits With Elaborate Sanitization Design for 3D TLC NAND Flash

Abstract

With the rising security concern on modern storage systems, the concept of data sanitization has been widely investigated recently. Among the existing works targeting data sanitization, an overwriting-based approach, namely one-shot sanitization, is one of the most efficient sanitization approaches. Nonetheless, we find that the one-shot sanitization approach would fail to achieve precise data sanitization for 3D TLC NAND flash, because of incurring undesired data errors. That is, how to simultaneously realize precise sanitization and high security with decent latency and reliability on emerging storage devices remains unsolved. This work proposes an elaborate sanitization design that skillfully manipulates the threshold voltage ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$V_{t}$</tex-math></inline-formula> ) distribution of sanitized pages. Not only does the proposed design achieve precise sanitization and high security, but it also enhances read performance and data reliability. Specifically, this work elaborately sanitizes data by merging specific <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$V_{t}$</tex-math></inline-formula> distributions of the target physical page on 3D TLC NAND flash. Besides, the proposed approach further takes lateral charge migration into consideration to improve data reliability. We conduct a series of experiments to evaluate our proposed approach on real 3D TLC NAND flash. The experiment results demonstrate the proposed approach can achieve elaborate data sanitization under various scenarios and improve read performance by 29%.