Smartd

Smartd is a daemon program that is part of the SMARTMonTools package. It monitors the Self-Monitoring, Analysis and Reporting Technology (SMART) status of hard disk drives and solid-state drives. By polling the SMART attributes of each device it can detect early signs of impending failure and can take predefined actions such as sending notifications, triggering system shutdown, or logging events.

Smartd was first released in the mid‑2000s and is widely used on Linux, FreeBSD, and other Unix-like operating systems. The daemon can be configured through a plain‐text configuration file that specifies which SMART attributes to monitor, the threshold values that indicate a problem, and the commands to execute when an alert is triggered. It can also schedule periodic SMART self‑tests and send the results via email or syslog.

Key features include the ability to monitor a variety of drive brands, support for custom rules written with SMART attribute IDs, and integration with system-wide notification systems such as notify-send or cron. Smartd can run in the background as a standard system service or be executed manually for ad‑hoc checks. Many Linux distributions include smartd as part of the default smartmontools installation, and it is often enabled by default in server distributions to provide continuous health monitoring.

According to the smartmontools documentation, smartd significantly reduces surprise data loss by providing early warning of disk degradation. It is commonly used by system administrators, data‑center operators, and home users who want to proactively protect storage assets.