Reclaim Unit Handle

Overview

A reclaim unit handle (RUH) is the Flexible Data Placement (FDP) construct a host writes through to steer data into separate physical reclaim units on an SSD. A modern FDP SSD typically exposes about eight reclaim unit handles, and writing hot versus cold data through different RUHs is how hosts achieve the data separation that lowers write amplification factor (WAF). Reclaim unit handles are the unit of data separation that Solidigm's multiple reclaim group FDP multiplies (across reclaim groups) into many more placement IDs, and the unit ScaleFlux proposes to isolate and overprovision independently.

A practical limit applies: assigning more workloads than there are natural classes of data to the remaining reclaim unit handles tends to hurt WAF more than it helps, because there is no further opportunity for data separation.