Sep 13, 2025 · Linux & Servers / Beginner · ~2 MIN READ

How to Monitor Disk Health with SMART

Notice disk problems before data loss occurs — smartctl basics, key warning attributes, and scheduled alerting.

Who This Is For

Beginner.

Think of it like your car’s check-engine light. A small warning today beats a breakdown on the highway next month.

What You’ll Build

SMART scheduled checks with alerting, or at minimum a documented manual review process.

Prerequisites

A Linux host with direct or USB-attached disks

Install smartmontools

$ sudo apt install smartmontools

Basic Commands

$ sudo smartctl -i /dev/sda      # device info
$ sudo smartctl -H /dev/sda      # health status
$ sudo smartctl -a /dev/sda      # full attribute report
$ sudo smartctl -t short /dev/sda
$ sudo smartctl -t long /dev/sda

Key Warning Indicators

Reallocated sectors, the drive has already had to work around bad sectors
Pending sectors, sectors waiting to be reallocated
Uncorrectable sectors, data loss has already occurred in that spot
Rising temperature trend
For NVMe: media errors in the health log

A “Passed” Status Is Not a Guarantee

SMART self-tests can pass while individual attributes show a worrying trend. Read the full attribute report, not just the pass/fail summary.

Schedule Tests with smartd

smartd (installed alongside smartmontools) runs scheduled tests and can email or webhook on warnings, configure it in /etc/smartd.conf.

When a Disk Shows Warning Signs

Confirm backups are current
Copy off any critical data immediately
Avoid running further stress tests if failure looks imminent
Replace the drive

Security & Backup Notes

SMART is an early-warning system, not a replacement for backups, a drive can fail catastrophically with little or no SMART warning

Troubleshooting

USB enclosures sometimes don’t pass SMART data through correctly, try -d sat or the enclosure-specific device type flag with smartctl

Lab Finish Line

SMART scheduled checks with alerting or a documented review process.