[RELEASE] ZFS Guardian - Smart Predictive Fan Control for your Roasting Drives

Apps and Virtualization
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Hello everyone,

I’ve been working on a small project to improve thermal management in ZFS-based storage servers. I originally built it for my own TrueNAS system, and after running it for a while I thought it might be useful for others in the community.

Tired of your CPU sitting at 35°C while your HDDs quietly climb past safe temperatures during a ZFS scrub?

Most motherboards and NAS systems control fans based solely on CPU temperature.
But in a dedicated storage server, your CPU might be idling while your disk array is under heavy load.

The result: your drives heat up silently during scrubs, resilvers, or large transfers — potentially shortening their lifespan.

Introducing ZFS Guardian: a lightweight Docker-based tool designed to manage cooling based on what actually matters in a storage server — disk activity and disk temperatures.

Why is this different?

:rocket: Predictive Pre-cooling
Instead of waiting for disks to get hot, ZFS Guardian monitors real-time ZFS throughput (zpool iostat).
If it detects heavy transfers (>100MB/s), it ramps up the fans before the heat builds up.

:brain: S.M.A.R.T. Integration
Reads real-time temperatures directly from HDDs, SSDs and NVMe devices.

:police_car_light: Hardware Safety Monitoring
Detects fan jams, abnormal temperature spikes (based on a 48h baseline), and “Ghost Disk” conditions.

:bar_chart: WebGUI Dashboard
Clean dark-mode interface with real-time charts (Chart.js) for temperatures, fan RPM and ZFS throughput.

:locked: Fail-safe Design
Includes TOTP-based 2FA, session management, and a safety mode that locks fans to 80% if disk monitoring fails.

Screenshots / UI

image
image1183×1202 67.3 KB

Quick Start (Docker Compose)

Requires privileged: true to access smartctl and hwmon for direct fan control.

services:
  zfs-guardian:
    image: ctagadev/zfs-guardian:latest
    container_name: zfs-guardian
    privileged: true
    restart: unless-stopped
    ports:
      - "48080:8000"
    volumes:
      - ./data:/app/data # Persistent storage for database and language files (create it in a dataset).
      - /dev/disk/by-id:/dev/disk/by-id:ro
      - /sys/class/hwmon:/sys/class/hwmon:rw

Get it now

Full documentation and source code:

:backhand_index_pointing_right: https://github.com/ctagadev/zfs-guardian

Includes full i18n support (English/Spanish templates included).

Keep those platters cool.

Feedback, suggestions and real-world testing are very welcome.
I’m especially interested in hearing how it behaves on different TrueNAS or ZFS setups.

1 Like
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really interesting! i will give it a try and report :smile:

Edit: unlucky for me, no fans are detected :slightly_frowning_face: this is sure related to my motherboard :pensive_face:

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Sounds great.

Feature request: Please consider making an TrueNAS app for easier use.

2 Likes
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Cool idea.

I personally don’t need it (simply because my HDD don’t get to what I would consider hot, even during scrubs), boot looks nice.

Only issue I take with is the predictive pre cooling. That just sounds like a silly idea made up by AI.

We would not do that for CPUs, just because they are at 100% usage. Simply because the temp will rise either way and the fans spin up. Also there is way too little stored heat to make a meaningful difference. So I can’t imagine a scenario where this would bring any benefit over simply ramping up the fans on current temps.

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There would, of course, be considerably more stored heat in a HDD than in a CPU.

1 Like