Multiple Reclaim Group FDP

Overview

Multiple reclaim group FDP is a Solidigm-proposed Flexible Data Placement configuration that multiplies the number of placement IDs by the number of reclaim groups — as many as the number of die — to give far finer data separation than single reclaim group FDP. Where single reclaim group FDP exposes only a handful of reclaim unit handles, a multiple-RG drive with one reclaim group per die turns a hypothetical 8 TB SSD's eight reclaim unit handles into 8 × 128 = 1,024 placement IDs. Hosts access this array through two strategies: individual PID (a write stream targets one placement ID) and reclaim group stripe (a stream is striped across a reclaim unit handle over multiple reclaim groups), which can be combined on one SSD.

The configuration delivers its benefit when the number of classes of data separation is large. In a hyperscale workload mixing cloud database tenants, AI checkpointing, and HDD caching, multiple reclaim group FDP achieved write amplification factor (WAF) of 1.01 in Solidigm's simulator and 1.07 on prototype hardware, versus 2.6 for single reclaim group mode and 3.06 for standard block mode. Beyond WAF, choosing the number of reclaim groups in a stripe tunes read/write bandwidth, and isolating workers improves quality of service by reducing die and channel contention.