Spinning rust and SSDs both fail predictably from heat first. The XDA piece on building an ESP32 display for drive temperatures kicked off a wave of homelab posts about the right way to watch a NAS that is not “open htop and squint.” We installed seven temperature and SMART-monitoring tools on a Ryzen-based TrueNAS Scale box and a Windows desktop with eight HDDs to figure out which ones actually surface drive thermals in a useful way, which alert before a drive degrades, and which ones run as a sidecar without eating the CPU.
The list mixes a polished SMART dashboard (Scrutiny), the foundational CLI tool every monitor wraps (smartmontools), a desktop GUI for the same data (GSmartControl), and three general-purpose monitors that include disk temperatures in their feed.
What to look for in a NAS drive temperature monitor
The category is mostly thin wrappers around smartctl. Five things separate a useful monitor from “just install smartmontools”:
- SMART attribute history. A spot temperature reading is fine. A 90-day chart of temperature, reallocated sectors, and pending sectors is what predicts failure.
- Alerting. The tool needs to email, push, or message you when a drive crosses a threshold. Manual dashboards do not save weekend trips home.
- Multi-drive view. Eight bays in a single chart, not eight terminal windows.
- Long SMART tests. Short tests run in minutes, long tests take hours. The good tools schedule and report both.
- Non-root pulls. Some tools want sudo for every poll. Scrutiny and Glances stay friendlier with their permission asks.
Quick comparison
| App | Best for | License | Platforms | Web UI |
|---|---|---|---|---|
| Scrutiny | SMART dashboard with history and alerts | MIT | Linux, Docker, Windows | Yes |
| smartmontools | CLI baseline every other tool wraps | GPL | Linux, macOS, Windows | No |
| GSmartControl | Desktop GUI for smartctl | GPL | Linux, Windows, macOS | No |
| Glances | Live system monitor with disk temps | LGPL | Linux, macOS, Windows | Optional web UI |
| Netdata | Full-stack metrics with disk thermals | GPL | Linux, FreeBSD, macOS | Yes |
| CrystalDiskInfo | Windows SMART dashboard | Freeware | Windows | No |
| HWiNFO64 | Deep Windows hardware sensors | Freeware | Windows | No |
The 7 best NAS drive temperature monitors
1. Scrutiny, best SMART dashboard with history and alerts
Scrutiny is the polished open-source web dashboard for SMART data, designed for homelabs that already run Docker. It collects SMART attributes from every drive, stores history in InfluxDB, and shows a per-drive page with temperature curves, failure-prediction metrics, and Backblaze drive-specific failure correlation. The Notify hooks send alerts to Discord, Telegram, Slack, Pushover, Apprise, and webhook endpoints. Setup is a single Docker Compose file, with the collector running on each NAS and the dashboard on whatever box has the spare CPU.
Where it falls short: Requires Docker (or the binary collector + dashboard pair). The web UI is fast but not customisable beyond what the project ships.
Pricing:
- Free: yes
- Paid: no
Platforms: Linux, Docker, Windows
Download: github.com/AnalogJ/scrutiny
Bottom line: The default pick for any homelab serious enough to run Docker. The Backblaze failure correlation is the single most useful predictive signal in the category.
2. smartmontools, best CLI baseline every other tool wraps
smartmontools is the upstream of nearly every SMART tool on this list. The smartctl binary reads attributes, runs short and long tests, and prints failure-prediction summaries. The smartd daemon watches the same drives and emails when thresholds cross. Most homelab guides default to a smartd.conf that pushes weekly long tests, daily short tests, and a temperature-alert threshold. No GUI, no web UI, but every other tool here speaks its output format.
Where it falls short: Pure CLI. Setting up the email path on a headless NAS takes a configuration round if your network does not already have a relay.
Pricing:
- Free: yes
- Paid: no
Platforms: Linux, macOS, Windows, BSD
Download: smartmontools.org
Bottom line: Install smartmontools regardless. The other tools surface the data more nicely, but smartctl is the source of truth.
3. GSmartControl, best desktop GUI for smartctl
GSmartControl is the GTK-based GUI front end for smartmontools. It lists every drive, shows the full attribute table, and walks you through running a short or long self-test from the menu rather than the command line. For a Linux desktop or workstation with a few internal drives, GSmartControl is the fastest way to check a drive without learning smartctl flags.
Where it falls short: Single-machine focus, no history or alerting. The desktop GUI matters less on a headless NAS than the web tools above.
Pricing:
- Free: yes
- Paid: no
Platforms: Linux, Windows, macOS
Download: gsmartcontrol.shaduri.dev
Bottom line: Pick this for a single-machine workstation where you want a GUI for ad-hoc drive checks.
4. Glances, best live system monitor with disk temps
Glances is the htop replacement that ships disk temperature, IOPS, and IO wait alongside CPU and memory. The default terminal UI is one screen; the optional web UI surfaces the same data in a browser. Glances reads hddtemp for spinning disks, smartctl for SSDs, and integrates with the InfluxDB exporter for long-term history. If you already use Glances for general monitoring, the disk-temperature column is free.
Where it falls short: Not a SMART dashboard. Glances surfaces temperature and a thin slice of SMART, not the full attribute set or failure prediction.
Pricing:
- Free: yes
- Paid: no
Platforms: Linux, macOS, Windows
Download: nicolargo.github.io/glances
Bottom line: The right pick if you already run Glances for system monitoring and want disk temps in the same view.
5. Netdata, best full-stack metrics with disk thermals
Netdata is the high-resolution metrics agent that ships pre-configured dashboards for almost every Linux subsystem, disk thermals included. The smartctl plug-in pulls SMART attributes on a schedule and graphs temperature, reallocated sectors, pending sectors, and lifetime hours. The alerting engine surfaces threshold crossings to email, Discord, Slack, PagerDuty, and a long list of others. The Netdata Cloud overlay (optional) lets you watch many nodes from one place.
Where it falls short: Heavier than Glances or Scrutiny because Netdata watches everything by default. Some teams disable the modules they do not need to keep the CPU footprint sane.
Pricing:
- Free: yes for the open core
- Paid: optional Netdata Cloud Pro for advanced multi-node features
Platforms: Linux, FreeBSD, macOS
Download: netdata.cloud
Bottom line: The pick for a homelab that wants a single monitoring agent across CPU, network, disk, and SMART, with thermals included.
6. CrystalDiskInfo, best Windows SMART dashboard
CrystalDiskInfo is the long-running Windows SMART utility that almost every PC builder has installed at least once. The single-window dashboard shows each drive’s health status, temperature, and the full attribute table. The notification daemon sends a tray alert when a drive crosses a configurable temperature or attribute threshold. Themed editions ship in pink, blue, and the famous “Shizuku” anime mascot version, none of which affect the actual functionality.
Where it falls short: Windows only, single-machine focus, no central dashboard. Polling cadence depends on the daemon staying loaded in the tray.
Pricing:
- Free: yes
- Paid: optional donation
Platforms: Windows
Download: crystalmark.info/en/software/crystaldiskinfo
Bottom line: The default Windows pick for one or two-drive checks. For a multi-drive NAS, layer a network monitor above it.
7. HWiNFO64, best deep Windows hardware sensors
HWiNFO64 is the freeware monitoring tool every Windows overclocker keeps in their toolkit. The sensors window surfaces every readable temperature on the machine, every voltage rail, every fan speed, and SMART data per drive. The logging output writes to CSV for long-term analysis, and the gadget integration pushes specific sensors to Rainmeter or AIDA64-style overlays. Drive thermals are part of the larger sensor picture, which is the right framing for a workstation that doubles as a NAS.
Where it falls short: The sensors window is dense. New users need an afternoon to learn the layout. No native cross-machine view.
Pricing:
- Free: yes for personal use
- Paid: Pro tier for business and remote-monitoring features
Platforms: Windows
Download: hwinfo.com
Bottom line: The right pick if drive thermals are one of many sensors you want to watch and the box runs Windows.
How to pick the right one
- Run smartmontools on every NAS regardless. It is the source of truth and the daemon is the simplest path to a “drive failing” email.
- Add Scrutiny on top if Docker is already running. The historical charts and Backblaze failure-prediction overlay are unique to it.
- Pick GSmartControl for a single-machine Linux desktop check.
- Pick Glances if you already use it for system monitoring and want disk temps in the same screen.
- Pick Netdata for a homelab that wants one agent across CPU, network, disk, and SMART, with alerting baked in.
- Pick CrystalDiskInfo for a single-drive Windows machine. Pair with the tray notifier for the alerting layer.
- Pick HWiNFO64 for a Windows workstation where drive thermals are one sensor among many.
FAQ
What temperature is too hot for a NAS drive?
Backblaze’s drive-failure data and most manufacturer specs agree: sustained operation above 50 °C shortens drive life noticeably, and operation above 55 °C is the threshold where failure rates climb sharply. Aim for the 30 °C to 45 °C band on spinning rust and well under 60 °C on consumer SSDs.
Does CrystalDiskInfo work for NVMe SSDs?
Yes. The newer CrystalDiskInfo releases read NVMe SMART attributes including the controller temperature, the composite temperature, and write endurance. The dashboard layout is the same for SATA and NVMe.
Can I monitor drive temperatures over the network?
Yes. Scrutiny is the easiest because the collector runs on each NAS and the dashboard runs centrally. Netdata can stream from many nodes to a single Netdata Cloud view. smartmontools alone does not have a network protocol; it relies on email from each node.
Is there an alternative to Scrutiny for ZFS pools specifically?
ZFS pools surface most drive health through zpool status and the kernel dmesg. Scrutiny still works because it reads SMART attributes directly from each disk. TrueNAS Scale ships its own dashboard that surfaces pool-level health alongside per-drive SMART, so a TrueNAS user may not need a separate dashboard.
Should I run long SMART tests on a NAS?
Yes, but schedule them. A long test reads every sector and takes several hours on a multi-TB drive. Most homelab guides schedule a long test once per month overnight and short tests once per week. smartmontools, Scrutiny, and Netdata can all kick the tests on a cron.