from dieTasse@feddit.org to selfhosted@lemmy.world on 16 May 08:00
https://feddit.org/post/12543528
Hi all, What is UPS input load and how can that affect the power draw of devices plugged into it?
Context: I have an Eaton UPS. Into it I plugged TP Link smart plug to measure how much my homelab draws (1 truenas server, 1 rpi and a switch). These draw about ~29 W when under low to medium load. Almost every day (different time) for couple of hours, however, the plug measure about 6-7 Watts more (~36 W). I have checked both linux devices and they were doing basically nothing. Then I looked into TrueNAS monitoring and noticed that the start and end of each event is exactly the same time when UPS input load is increased from 0 % to ~6 %.
What is this UPS input load and how is it possible it affects measurements by a device that is plugged into it (the UPS) - NOT the other way around? Thank you
threaded - newest
So what is the TrueNAS server doing at this time? Have you checked the logs?
I would image it might be some backup, snapshotting or optimization.
Truly nothing. I haven’t set snapshots yet, I have TrueCloud backup but thats at midnignt. I have checked htop and there is virtually zero activity (same as when the power draw is 29 W). I have only two apps on truenas and they also didn’t do any indexing or anything). As mentioned above the only difference that I spotted so far is the ups input load and the times of event start/end match perfectly in all cases (but then again UPS is powering the tp plug and on, not the other way around).
UPS devices normally uses wall (input) power, and switches to battery when input voltage is out of the target thresholds. So, input.load should represent the percentage of current wall power (in VA) relative to UPS’s max rated input power (VA). If your devices uses more power, input power from wall should increase as well.
If it’s peaking in certain times, it could be due some scheduled job temporarily increase CPU frequency, or automated tasks like file system snapshot might power-up/spin drives longer than regular usage.
Ahaa, so what you are saying that me seeing the input load on UPS is not the cause of the measured power consumption but just a “symptom”. That something (be it TrueNAS/rpi/switch) really draws more. How can I do a thorough analysis of what the devices do? Normally I check logs and htop and see they are just chilling. I check cpu, i/o and network and I thought that it should be pretty good indicator of if something is happening. Especially when its 6 Watts more thats like whole another rpi 😀
It’s weird to do this daily, but it’s possible that the UPS is doing a self test, which would drain the battery a little and the load is from charging it back up.
Same as above. The TP link that measure the power is plugged into the UPS not the other way around. The UPS is directly in the wall plug. So even if the UPS drawn 100 Watts it shouldn’t show on the TP Link.
What’s in the UPS log?
Good question, how do I access the UPS logs? In TrueNAS (and in home assistant) I just see the measured values.
The UPS needs some power to keep its batteries full. Could be that it’s triggering off some threshold to do a charge cycle instead of just running a constant trickle. I’ve noticed that my laptop and phone charge that way, for example.
But the TP link that measure the power is plugged into the UPS not the other way around. The UPS is directly in the wall plug.