One mount.
Many disks.
Explicit rules.

Tired of your apps waking up all your drives just to list a directory? Common examples are media library scans (Plex/Jellyfin) and NVR retention workflows. PolicyFS unifies multiple disks under one mountpoint, routes reads and writes by explicit rules, and keeps archive disk metadata in a local index so scans don't needlessly spin up sleeping drives.

Get started See use cases

Features

Storage behavior you can reason about

Policy-based routing

Route reads and writes by path pattern — one rule for library/**, another for everything else. Write policies (first_found, most_free, least_free) choose a write target. Path-preserving mode prefers targets where the parent directory exists to reduce scattering.

Fewer unnecessary wakeups (optional)

For archive disks, PolicyFS can keep metadata-heavy scans from touching sleeping drives unnecessarily. You can run maintenance jobs during a scheduled window (for example, overnight) when waking disks is acceptable.

Built-in maintenance cycle

PolicyFS includes maintenance jobs for tiered storage: move colder files to an archive tier, apply queued changes, and refresh metadata. This works well with systemd timers and a simple “maintenance window” model.

Workflow

Write fast, archive later

One path for your apps

Expose a single mountpoint and keep your directory layout stable as your storage grows.

Put new writes on the fast tier

Use explicit routing rules so new files land on SSDs (or your preferred fast tier).

Run maintenance on your schedule

Move colder files to archive disks and apply queued changes during a maintenance window.

Keep archive disks quieter (optional)

When configured, metadata-heavy scans can avoid touching sleeping archive disks unnecessarily.

Use cases

A good fit for mostly-static libraries and archive tiers

Media servers are a common example, but PolicyFS is also useful anywhere you want one merged path across many disks, explicit placement rules, and a predictable maintenance window.

Media libraries

Keep a single path for your library while scaling storage over time. Reduce the “scan wakes every disk” problem by separating normal access from scheduled maintenance.

NVR / CCTV retention

Write new footage to a fast tier, then migrate older recordings to an archive tier on a schedule without changing paths.

See configuration examples →

Comparison

pfs vs mergerfs

mergerfs is a mature FUSE union filesystem with broad POSIX coverage and a large install base. pfs is narrower and focuses on explicit storage placement and metadata behavior. If you need maximum compatibility or complex workloads, mergerfs is likely a better fit.

Feature	pfs	mergerfs
FUSE-based storage pooling	✓	✓
Path-pattern routing rules	✓	—
Multiple write target policies	✓	✓
Optional metadata index (reduced HDD wakeups)	✓	—
Queued changes (applied later)	✓	—
Built-in tiered storage mover	✓	—
POSIX feature coverage	partial	✓
Maturity & ecosystem	newer	established

pfs trades POSIX breadth for explicit, inspectable behavior. mergerfs covers more edge cases and has a longer track record.

Configuration

One YAML file, multiple mounts

A minimal two-tier setup: SSD as a write cache, HDDs as indexed archive storage.

# /etc/pfs/pfs.yaml
mounts:
  media:
    mountpoint: /mnt/pfs/media  # single path your apps use

    storage_paths:
      - id:   ssd1
        path: /mnt/nvme/cache  # new files land here first

      - id:      hdd1
        path:    /mnt/hdd1/media
        indexed: true  # metadata cached in SQLite; disk stays asleep

      - id:      hdd2
        path:    /mnt/hdd2/media
        indexed: true

    routing_rules:
      - match:         "**"
        targets:       [ssd1, hdd1, hdd2]
        write_policy:  most_free  # new files go to the disk with most free space

One mount.Many disks.Explicit rules.