Andrew Mercer
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sudo dnf install smartmontools        # or apt-get install smartmontools

sudo smartctl -i /dev/sda             # identity: model, serial, firmware, SMART support
sudo smartctl -H /dev/sda             # overall health verdict
sudo smartctl -a /dev/sda             # everything: attributes, error log, self-test log
sudo smartctl -x /dev/sda             # extended (more log pages)

The verdict looks like:

=== START OF READ SMART DATA SECTION ===
SMART overall-health self-assessment test result: PASSED

"PASSED" is not a guarantee. A drive only reports FAILED when a threshold is crossed, which often happens late. Read the attributes:

  • Reallocated_Sector_Ct, Current_Pending_Sector, Offline_Uncorrectable: any non-zero and rising value is a warning to replace the drive.
  • UDMA_CRC_Error_Count: cable or connector problems, not the platters.
  • For NVMe (smartctl -a /dev/nvme0): Percentage Used, Available Spare, and Media and Data Integrity Errors.

Self-tests

sudo smartctl -t short /dev/sda       # about 2 minutes
sudo smartctl -t long /dev/sda        # hours; runs in the background
sudo smartctl -l selftest /dev/sda    # results

Monitoring

smartd (same package) checks drives periodically and emails or logs problems. Enable it with sudo systemctl enable --now smartd (service name smartmontools on Debian). Behind hardware RAID controllers, tell smartctl how to reach the physical disks (-d megaraid,N, -d cciss,N). See also badblocks and hdparm.