TrueNAS CORETrueNAS CORE Nightly Development Documentation
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Configuring UPS

An Uninterruptible Power Supply (UPS) is a power backup system that ensures continuous electricity during outages, preventing downtime and damage.

TrueNAS uses NUT (Network UPS Tools) to provide UPS support. For supported device and driver information, see their hardware compatibility list.

Report UPS bugs and feature requests to the NUT project.

Setting Up UPS Service

Connect the TrueNAS system to the UPS device. Configure the UPS service by going to Services, finding the UPS entry, and clicking edit edit icon.

TrueNAS Enterprise
TrueNAS High Availability (HA) systems are not compatible with uninterruptible power supplies (UPS).
UPS Service Screen
Figure 1: UPS Service Screen (Top)
UPS Service Screen
Figure 2: UPS Service Screen (Bottom)

See UPS Screen for more information on UPS settings. Some UPS models can be unresponsive with the default polling frequency. This shows in TrueNAS logs as a recurring error like libusb_get_interrupt: Unknown error. The default polling frequency is two seconds. Decrease the polling frequency by adding an entry to Auxiliary Parameters (ups.conf): pollinterval = 10. This should resolve the error.

upsc(8) can get status variables like the current charge and input voltage from the UPS daemon. Run this command from the shell using the syntax upsc ups@localhost. The upsc(8) manual page has other usage examples.

If the hardware supports sending the command, upscmd(8) can send commands directly to the UPS. Only users with administrative rights can administer these commands. Create these users in the Extra Users field.

How do I find a device name? Determine the correct device name for the UPS. Go to System > Advanced and select Show console messages. Plug in the USB device and look for a /dev/ugen or /dev/uhid device name in the console messages.
Can I attach multiple computers to one UPS? A UPS with adequate capacity can power multiple computers. Connect one computer to the UPS data port with a serial or USB cable. This primary system makes UPS status available on the network for other computers. The secondary computers receive UPS status data from the primary computer. The secondary computers receive power from the UPS. See the NUT User Manual and NUT User Manual Pages.