MCFlash: Bulk Bitwise Processing in 3D NAND with Dynamic Sensing and Multi-level Encoding

TL;DR

MCFlash enables error-free, in-place bulk bitwise operations directly within commercial 3D NAND flash chips using standard instructions, multi-level encoding, and dynamic voltage tuning, achieving high durability and low error rates.

Contribution

Introduces MCFlash, a practical method for executing bulk bitwise operations inside off-the-shelf 3D NAND flash using standard commands and novel encoding techniques.

Findings

Error-free bitwise operations demonstrated on various NAND chips

Over one billion operations sustained on fresh blocks

Bit-error rates below 0.015% after 10,000 P/E cycles

Abstract

This paper presents MCFlash, a practical and immediately deployable technique for executing bulk bitwise operations directly within commercial off-the-shelf(COTS) 3D NAND flash chips. MCFlash relies solely on standard user-mode instructions, combining Multi-Level Cell (MLC) data encodings with dynamically tuned read reference voltages to execute in-place bitwise operations. We evaluate MCFlash across diverse NAND flash chips, both floating-gate and charge-trap variants, from different generations. Our results represent the first demonstration of error-free, on-chip bitwise operations, sustaining over one billion operations on fresh blocks and maintaining bit-error rates below 0.015% even after 10,000 program/erase (P/E) cycles.