SMART Check Reference

All parameters, thresholds, and configuration options for the S.M.A.R.T. check in octoja.

Written By Erdinc Akay

Last updated 26 days ago

This article describes the prerequisites, configuration, and behavior of the S.M.A.R.T. check. In the check catalog it appears as SMART Disk Health (DE: SMART Festplattengesundheit).

Prerequisites

The check uses smartmontools (specifically the smartctl command) to read SMART data. On Linux, the octoja agent auto-installs it before the first run using whichever package manager is present (apt-get, dnf, yum, pacman, apk, or zypper). If none of these are available, install smartmontools manually. On Windows and macOS, no additional software is needed.

Configuration Fields

Field	Type	Required	Default	Description
Monitor all disks	bool	No	true	When enabled (the default), the agent runs `smartctl --scan` and monitors every discovered physical disk. When disabled, the Disks to monitor field below is used instead
Disks to monitor	string[]	No	—	Explicit list of device paths to monitor (only used when Monitor all disks is off). Examples: `/dev/sda` (Linux), `/dev/disk0` (macOS), `/dev/pd0` (Windows)
Temperature warning — HDD (°C)	number (°C)	No	50	A spinning hard disk at or above this temperature triggers a Warning. Applies to HDDs only
Temperature error — HDD (°C)	number (°C)	No	60	A spinning hard disk at or above this temperature triggers a Critical alert. Applies to HDDs only
Temperature warning — SSD / NVMe (°C)	number (°C)	No	70	A solid-state drive (SATA SSD, NVMe, M.2) at or above this temperature triggers a Warning. Solid-state drives tolerate more heat than spinning disks
Temperature error — SSD / NVMe (°C)	number (°C)	No	80	A solid-state drive (SATA SSD, NVMe, M.2) at or above this temperature triggers a Critical alert
Max reallocated / media errors	number	No	0	Reallocated sectors (ATA) or media errors (NVMe) above this threshold trigger a Critical alert (the default of 0 means any non-zero count alerts)

All threshold fields only appear in the check editor after enabling Show advanced options. Drives that report no rotation rate are treated as solid-state and use the SSD / NVMe thresholds. The check runs every 60 minutes; the interval is not configurable in the check editor.

Monitored SMART Attributes

Attribute	What it means
Overall Health	A pass/fail summary from the drive firmware. A Fail means the drive itself predicts imminent failure
Reallocated Sectors (ATA attribute 5) / NVMe media_errors	Bad sectors that the drive remapped to spare areas (or, for NVMe, the media-error counter). Any non-zero value indicates physical deterioration
Temperature	Drive temperature in Celsius. High temperatures reduce drive lifespan and can indicate poor ventilation
Power-On Hours	Total hours the drive has been running. Useful for estimating remaining lifespan (most drives are rated for 30,000–50,000 hours)
Model, Serial, Capacity	Drive identification and size, reported alongside health data for inventory context

Alert triggers

Condition	Severity
Overall health = Fail	Critical
Reallocated sectors (ATA) or media errors (NVMe) exceed Max reallocated / media errors (default 0 — any non-zero count alerts)	Critical
An individual SMART attribute is failing now or has failed in the past	Critical
An NVMe drive reports a critical warning (spare capacity low, reliability degraded, read-only mode, volatile-memory backup failure, or persistent-memory-region failure)	Critical
A SCSI/SAS drive's firmware reports an impending failure	Critical
A disk the device previously reported is no longer detected (it may have failed or been removed)	Critical
HDD temperature ≥ Temperature error — HDD (default 60 °C); SSD/NVMe temperature ≥ Temperature error — SSD / NVMe (default 80 °C)	Critical
HDD temperature ≥ Temperature warning — HDD (default 50 °C); SSD/NVMe temperature ≥ Temperature warning — SSD / NVMe (default 70 °C) — in each case below the matching error threshold	Warning
SMART data cannot be read from an explicitly configured disk	Error (for that disk)
The `smartctl` binary is unavailable on the device	Error
Disks were found and queried, but none returned usable SMART data (every query dropped, so the reported disk list ends up empty)	Warning

Notes

SMART data is only meaningful for physical disks. Virtual disks typically return no usable data; when Monitor all disks is enabled, auto-discovery filters out phantom USB enclosures but does not otherwise validate that a device is physical.
SSDs and HDDs both support SMART but report different attributes. Both are interpreted correctly.
A device with no SMART-capable disks — auto-discovery finds none, or Monitor all disks is off and the explicit disk list is empty — reports OK, not a Warning. A Warning is raised only when disks were found but every query failed to return usable data.
The "disk is no longer detected" alert is evaluated across successive runs rather than by a single scan: octoja compares each run against the previous one, so a disk that drops off the bus is only flagged after it has been missing for a short debounce window (about 5 minutes), which ignores a one-off scan glitch. A disk that stays missing for more than a few days ages out and stops alerting, so a genuinely decommissioned drive does not alarm forever.

See also: Configure a SMART Check