Backblaze publishes its Drive Stats every quarter, and the last thirteen years of data agree on one thing: most drive failures happen after year four. Some models never make it that long. Others last a decade. The way to tell early is SMART attribute monitoring, but only a few attributes actually predict failure and only a few tools surface them the right way.
We tested seven SMART-monitoring tools across Windows, Linux, and macOS to find which ones catch the meaningful signals (reallocated sectors, pending sectors, uncorrectable errors, power-on hours crossing thresholds) and quiet the noise. Below is what each does, which platform it fits, and which combination gives you enough warning to replace a drive before it takes data with it.
What to look for in a HDD failure prediction tool
Not every SMART attribute matters. The right tool tells you which ones do.
- Backblaze-derived thresholds. SMART 5 (Reallocated Sectors), 187 (Reported Uncorrectable Errors), 188 (Command Timeout), 197 (Current Pending Sectors), 198 (Offline Uncorrectable) are the five that best predict failure. Tools that ignore these five are not doing the job.
- Long-term trend tracking. A single reallocated sector today matters less than 5 new ones per week. History plots reveal drift.
- Alerting. Email, push, or webhook. A GUI that only warns while you look at it is not useful.
- Test scheduling. Short and long SMART self-tests need to run monthly. Automation is table stakes.
- NVMe support. NVMe SMART attributes differ from SATA. Tools that only understand SATA are missing half the modern install base.
Quick comparison
| App | Best for | Platforms | Free plan | Starting price/mo | Rating |
|---|---|---|---|---|---|
| Scrutiny | Multi-drive dashboard with Backblaze thresholds | Docker, Linux | Full free | Free | 4.7 |
| smartmontools | CLI SMART toolkit that everything else wraps | Windows, macOS, Linux, BSD | Full free | Free | 4.7 |
| CrystalDiskInfo | Windows GUI classic | Windows | Full free | Free | 4.6 |
| Hard Disk Sentinel | Windows GUI with strong prediction | Windows | Trial | About $40 one-time Pro | 4.7 |
| Disks (GNOME) | Built into GNOME Linux | Linux | Full free | Free | 4.3 |
| GSmartControl | Cross-platform smartmontools GUI | Windows, macOS, Linux | Full free | Free | 4.4 |
| DriveDx | Best macOS-native SMART monitor | macOS | Trial | About $20 one-time | 4.6 |
The apps
1. Scrutiny — Best multi-drive dashboard
Scrutiny wraps smartmontools with a modern web dashboard that uses Backblaze’s failure prediction data. Each drive gets a health score based on the SMART attributes Backblaze publishes as the strongest failure predictors, and trend graphs show whether a drive is drifting toward trouble.
Docker deployment is the standard install path. Point it at every drive in a NAS or homelab and one dashboard covers the fleet.
Where it falls short: Docker-only in practice (native binaries exist but are undertested). Setup takes 20 minutes.
Pricing:
- Free: Open source
- Paid: None
Platforms: Docker (runs anywhere Docker runs)
Download: Scrutiny
Bottom line: The default pick for anyone with more than three drives to monitor. Backblaze-derived thresholds mean signal, not noise.
2. smartmontools — Best CLI toolkit
smartmontools is the base layer: smartctl reads raw SMART attributes, smartd monitors in the background and sends email or runs scripts on threshold breach. Every other tool on this list (except CrystalDiskInfo and DriveDx) uses smartmontools underneath.
For a headless server, smartd plus a small email hook is the minimum viable monitoring. Runs on FreeBSD, Linux, macOS, Windows, and anything else with POSIX-ish tools.
Where it falls short: No GUI. Configuration is text files. Alerting is DIY.
Pricing:
- Free: Open source
- Paid: None
Platforms: Windows, macOS, Linux, BSD, Solaris
Download: smartmontools
Bottom line: Install this on every server. Wrap it with Scrutiny, Netdata, or a homegrown script for alerting.
3. CrystalDiskInfo — Best Windows GUI classic
CrystalDiskInfo shows every SATA and NVMe drive’s SMART data, health status, temperature, and firmware in one window. Colour-coded status (blue = good, yellow = caution, red = bad) covers the case where you glance at it once a month.
The tool ships with several sub-editions: standard, Shizuku (anime), and Kurei Kei (mecha). All are identical under the hood.
Where it falls short: Windows only. No trend history without exporting to CSV manually. Alerts require the app to be running.
Pricing:
- Free: Open source
- Paid: None
Platforms: Windows
Download: CrystalDiskInfo
Bottom line: Best pick for a Windows workstation. Run it at login, glance at it once a month.
4. Hard Disk Sentinel — Best commercial Windows SMART tool
Hard Disk Sentinel goes deeper than CrystalDiskInfo with per-drive health percentage, performance percentage, and estimated remaining lifetime. It ships a rich reporting layer (HTML, XML, CSV), disk performance benchmarks, and surface tests.
The prediction model uses more attributes than the Backblaze five, and the developer publishes a detailed methodology.
Where it falls short: Paid. Trial is fully functional; Pro is about $40 one-time. Interface is dense.
Pricing:
- Free: 30-day trial
- Paid: About $40 one-time Pro, family and business licenses higher
Platforms: Windows
Download: Hard Disk Sentinel
Bottom line: Best pick for anyone willing to pay once for deeper Windows monitoring than CrystalDiskInfo offers.
5. Disks (GNOME) — Best built into Linux
Disks (the GNOME Disks app, gnome-disk-utility) reads SMART data and runs self-tests from a friendly GUI. Every GNOME-based distro ships it by default. KDE users have the equivalent in Partition Manager plus KDiskMark.
For a Linux desktop where you want to check drive health once in a while, it is the “already there” answer.
Where it falls short: No trend tracking. No alerting. Only shows the current snapshot.
Pricing:
- Free: Open source
- Paid: None
Platforms: Linux (GNOME)
Download: Bundled with GNOME; see GNOME Disks
Bottom line: Best pick for casual on-demand SMART checks on a GNOME Linux desktop. Pair with Scrutiny or smartd for actual monitoring.
6. GSmartControl — Best cross-platform smartmontools GUI
GSmartControl is a portable GUI wrapper around smartmontools. Same data, same self-tests, but with a Windows/Mac/Linux GUI. It shows the SMART attribute table with human-readable descriptions and colour coding.
Great for anyone who wants smartmontools capability without the CLI.
Where it falls short: No monitoring or alerting; on-demand only. Interface is functional but dated.
Pricing:
- Free: Open source
- Paid: None
Platforms: Windows, macOS, Linux
Download: GSmartControl
Bottom line: Best pick when you want smartmontools information on a machine without opening a terminal.
7. DriveDx — Best macOS-native SMART monitor
DriveDx is the macOS answer to CrystalDiskInfo. Native app, per-drive health percentage, SSD-specific attributes (wear leveling count, endurance remaining), and menu bar warning icons when a drive’s health dips.
It supports both internal drives and external USB/Thunderbolt drives via smartmontools underneath.
Where it falls short: Paid. Trial is limited. macOS only.
Pricing:
- Free: 14-day trial
- Paid: About $20 one-time, family license about $30
Platforms: macOS
Download: DriveDx
Bottom line: Best pick for macOS users who want proper SMART monitoring including external drives.
How to pick the right one
If you have more than three drives across machines: Scrutiny in Docker. Dashboards win over per-machine tools fast.
If you run a Linux server: smartmontools with smartd configured for email alerts. Free, reliable, headless.
If you want a Windows workstation snapshot: CrystalDiskInfo. Free, fast, glanceable.
If you want deeper Windows analysis: Hard Disk Sentinel. Pay once, monitor everything.
If you are on macOS: DriveDx. Best in class for the platform.
If you want the free cross-platform pick: GSmartControl. Same data as the paid tools, unified UI.
FAQ
Can SMART actually predict drive failure? Sometimes. Backblaze’s research says about 76% of drives that failed showed SMART warnings in the days or weeks before. The other 24% failed with no warning at all. SMART is necessary but not sufficient.
Which SMART attributes matter most? Backblaze’s analysis flags SMART 5 (Reallocated Sectors), 187 (Reported Uncorrectable Errors), 188 (Command Timeout), 197 (Current Pending Sectors), and 198 (Offline Uncorrectable). A non-zero value on any of these is a caution flag; growing values are a red flag.
How often should I run SMART self-tests? Short tests weekly (2-5 minutes), long tests monthly (2-8 hours for a 4TB drive). Most monitoring tools schedule both automatically.
What is the best free SMART monitoring tool? Scrutiny for multi-drive dashboards, smartmontools for headless servers, CrystalDiskInfo for Windows. All three are free with no paid tier.
Does SMART monitoring work over USB? Sometimes. USB enclosures that pass SMART commands through work fine. Ones that don’t return “not supported” errors regardless of the tool. Enclosures with UASP support are more likely to work.
Should I replace a drive after the first reallocated sector? No. A single reallocation is normal wear. Two or more per week, or any pending sectors, is when you back up and plan replacement. Set the threshold in your monitoring tool.