Mechanism
WAF ↔ Wear Trade-off
What it shows. Each point is one (engine, trace): WAF on the x-axis (write cost) against DoEC on the y-axis (wear spread). Colour encodes the engine.
Why it matters. The two headline costs of an FTL — write amplification and wear concentration — do not always move together. This view exposes engines that buy low WAF at the price of uneven wear (or vice-versa), which is exactly the design trade-off an SSD architect must navigate.
What we found
- Low WAF does not guarantee even wear. The cloud of points is not a straight line — engines at similar WAF can differ markedly in DoEC, and vice-versa.
- Conventional superblock GC lands at high WAF and high wear spread (worst of both) on real traces; FDP-PI/II cluster toward low WAF with moderate wear.
- The frontier is what an FTL designer optimises: this plot names, per (engine, trace), who is on it and who is dominated.
