Overprovisioning

Overview

Overprovisioning is the practice of reserving spare SSD capacity to reduce garbage collection and lower write amplification factor (WAF). At the 2025 OCP Global Summit FDP panel, speakers gave it a pointed framing: using overprovisioning to hit WAF of one is "sort of cheating," because it gives drives more opportunity to reduce garbage collection rather than achieving the gain through data placement. The critique sharpened against rival data-placement technologies, which the panel said need host overprovisioning (e.g. 16%) to maintain WAF of one at capacity — meaning the headline metric "really doesn't mean much" once that cost is counted. FDP, by contrast, was presented as approaching WAF of one without paying that overprovisioning tax.

ScaleFlux proposed bringing overprovisioning under explicit FDP management rather than treating it as a shared pool: a fairly overprovision grant caps the physical space each reclaim unit can use based on RU capacity and triggers garbage collection by per-RU consumption rather than overall free blocks, making reclaim-unit life more predictable, with a prioritized variant for differentiated workloads.