User Space FTL

Overview

A user-space Flash Translation Layer (FTL) runs the flash mapping and management logic in host user space rather than inside drive firmware. In Meta's first QLC server, Pure Storage's DFMs use a user-space FTL that gives Meta the flexibility to change indirect unit (IU) sizes on-the-fly, optimizing performance for evolving workloads without hardware or firmware changes. Because the layer lives in software, Meta's software team could increase host-side parallelism — adding write buffering and coalescing — to improve overall system performance for QLC workloads. The user-space FTL is the mechanism that lets the host treat the server as a single large SSD, underpinning capabilities such as cross-drive RAID and workload-tuned write management.