On Enduring More Data Through Enabling Page Rewrite Capability on Multi-level-cell Flash Memory

The technology of NAND flash memory grows swiftly in response to the huge and rapidly changing storage market in recent years. Meanwhile, the demand for large amounts of data is also growing at an unprecedented scale. How to store more and more data over flash-based systems in a cost-effective way presents immense pressure and challenges to the system design. This motivates us to propose a breakthrough solution on the existing multi-level-cell flash memories such as TLC, being adopted in the mainstream solidstate drives. More specifically, we propose a durable management design through enabling page rewrite capability and incorporate it with the existing flash translation layer to achieve enduring more data written, even beyond the theoretical limit. Moreover, our management design further considers the adverse effect brought by disturbance, which could usually deteriorate the data correctness. The encouraging results through a series of experiments demonstrate the feasibility and the capability of our design. With the best setting we studied, the total amount of data that can be written into the system could be improved up to 2.14 times the baseline without adding any hardware cost.