A case for QLC SSDs in the data center

This post makes a case for adopting QLC SSDs in Meta's data centers as a new storage tier. It details the technical rationale, comparing QLC to HDDs and TLC SSDs in terms of density, performance, power efficiency, and cost. It discusses hardware considerations, such as form factors (E1.S vs. U.2) and the need for more performant CPU, memory, and network subsystems to leverage QLC's density. It also outlines software adaptations required, including handling higher throughput expectations and tuning rate controllers and I/O schedulers to manage the significant read/write throughput delta characteristic of QLC SSDs. Meta is actively collaborating with partners like Pure Storage and other NAND vendors to integrate QLC solutions.