Documentation

Technical Reference

Core concepts, glossary, and ecosystem readiness.

What is FDP?

Flexible Data Placement is an NVMe standard feature that assigns Placement ID (PID) tags to write requests, directing the SSD to physically separate data with different lifetimes and access patterns. This prevents data mixing within erase blocks, reducing Garbage Collection overhead and Write Amplification Factor.

Why FDP Matters

SSDs use flash memory, which cannot overwrite data in place. GC must relocate valid data and perform additional writes to reclaim space, causing WAF to rise. When short-lived and long-lived data share the same erase blocks, GC overhead compounds—degrading both performance (especially p99 latency) and drive endurance. FDP allows the host to proactively tag writes with group identifiers, guiding the SSD to physically separate data at the erase block level itself.

FDP vs Hot/Cold Tiering

	Hot/Cold Tiering	FDP
Approach	Reactive data migration	Proactive write-time tagging
Granularity	Cache layer level	Erase block level
GC Control	Indirect	Direct physical separation
Classification	Binary (hot/cold)	Multi-class (DataFount: 6-class)

“FDP-Based SSD Slicing: A logical partitioning technique in which the host assigns PID tags to I/O operations using the NVMe FDP feature, directing the SSD to route data into distinct Reclaim Unit pools.”

Input Feature Reference

A: I/O Pattern Features

op_type — Operation type: read / write / append

io_size — Request size (4KB–1MB+)

rw_ratio — Read-to-write ratio (sliding window)

sequential_score — Sequentiality from offset deltas

overwrite_rate — Rewrites to same key/offset

burstiness — Temporal concentration

update_frequency — Updates per record/key

B: Data Semantic Features

object_type — secret / metadata / audit_log / cache / blob

sensitivity — LOW / MED / HIGH

ttl_hint — short / medium / long

action_context — login, autofill, approval, policy_update, audit_write, attachment_upload

C: System/Policy Features

qos_tier — latency-critical / normal / background

requires_approval — true / false

network_zone — corp / external

device_trust — trusted / restricted / blocked

Group C features are for mature policy engine integration only. MVP requires Groups A and B.