Comparing the Reliability of Solid-State Drives Based on TLC and QLC NAND Flash Memories (Invited)

This paper reviews the reliability of Solid-State Drives (SSDs) based on NAND Flash memory with a focus comparing enterprise SSDs using TLC and QLC NAND. The paper analyzes various datasets including internal qualification methods and field studies. The data indicates that QLC SSDs have similar reliability to TLC SSDs, when NAND reliability mechanisms are sufficiently mitigated. Tradeoffs related to NAND differences and reliability mitigations and the resulting effect on performance, QoS, and endurance are highlighted. QLC NAND is a relatively new technology and there is limited published reliability data. The authors believe this is the first published field data for QLC-based enterprise SSDs.