src/health/guides/systemdunits/systemd_device_unit_failed_state.md
### Understand the alert
This alert is triggered when a `systemd device unit` enters a `failed state`. If you receive this alert, it means that a device managed by `systemd` on your Linux system has encountered an issue and is currently in a non-operational state.
### What is a systemd device unit?
`Systemd` is a system and service manager for Linux operating systems. A `device unit` in `systemd` is a unit that encapsulates a device in the system's device tree (e.g., `/sys` directory). The device units are used to automatically discover and manage devices present on the system.
### What does a failed state mean?
A `failed state` implies that the device has encountered an issue and is currently non-operational. The problem could be related to hardware, driver, or configuration issues.
### Troubleshoot the alert
1. Identify the failed device unit:
Check the `systemd` status for failed units using the following command:
```
systemctl --failed --type=device
```
This will show you the list of device units that are currently in a failed state.
2. Check logs for errors:
Use the `journalctl` command to check the logs for any error messages related to the failed device unit. For instance, if the failed unit is `example.device`, you can execute:
```
journalctl -xe -u example.device
```
This will show you the logs with any error messages that will help you identify the root cause of the failure.
3. Fix the issue:
Depending on the results from the previous steps, you might need to:
- Check the hardware connections and make sure they are properly connected.
- Update or reinstall the device driver.
- Check and correct device configurations if needed.
4. Restart the device unit:
Once the issue has been fixed, restart the device unit using `systemctl`:
```
sudo systemctl restart example.device
```
Replace `example.device` with the specific device unit name.
5. Validate the fix:
Check if the device unit is now operational by executing the following command:
```
systemctl status example.device
```
This should show you that the device unit is now active and running properly.
### Useful resources
1. [Systemd Device Units](https://www.freedesktop.org/software/systemd/man/systemd.device.html)