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ups on truenas1

truenas1 uses its built in UPS service, which is NUT, as the server for the basement UPS. checked against TrueNAS 26.0.0-BETA.3 and NUT 2.8.1.

the service

System > Services > UPS.

field value
Identifier ups-truenas
UPS Mode Master
Driver the RMCARD205 entry, which uses snmp-ups
Port or Hostname 192.168.1.72
Monitor User upsmon
Monitor Password its own password
Remote Monitor on
Shutdown Mode UPS reaches low battery
Power Off UPS off
Host Sync 15

Auxiliary Parameters (ups.conf):

snmp_version = v3
secLevel = authPriv
secName = nutups
authProtocol = SHA
privProtocol = AES
authPassword = <the auth key set on the card>
privPassword = <the privacy key set on the card>
ignorelb
override.battery.charge.low = 25
override.battery.runtime.low = 240
  • the card only answers SNMPv3, so the login goes in the auxiliary parameters
  • Remote Monitor makes upsd listen on the LAN, port 3493, so PeaNUT and Home Assistant can read it. NUT has no login for reads: anything on the LAN can read the UPS state. reads cannot change anything
  • ignorelb makes the driver ignore the UPS's own low battery flag, which comes too late, and report low battery when the charge is under 25% or the runtime estimate is under 4 minutes. with Shutdown Mode on UPS reaches low battery, that is when truenas1 shuts down
  • Power Off UPS is off, so the UPS stays on after truenas1 has shut down. it also feeds the basement network equipment. the cost: if mains returns before the battery is flat, truenas1 does not see power come back and stays off until someone starts it

check it

from another machine:

printf 'LIST VAR ups-truenas\nLOGOUT\n' | nc -w 5 192.168.1.86 3493

ups.status should be OL (on mains), and ups.load and battery.runtime should match the UPS's own display.

when it shuts down

on battery, at 25% charge or 4 minutes of runtime, whichever comes first.

truenas1 takes 72 seconds to shut down, measured, apps and pools included. 4 minutes is about three times that. the runtime is 14 to 15 minutes idle and 8 minutes during a model run, so in a model run the threshold is reached sooner.

upsc ups-truenas@localhost shows the thresholds as battery.charge.low and battery.runtime.low, and driver.flag.ignorelb: enabled.