EX4100 OS5 shutdown when UPS battery low

I’ve successfully gotten my EX4100, powered through a CyberPower UPS, to get UPS status from the UPS. In my particular case the NAS is a slave to a NUT server that talks directly to the UPS, but I’d expect the answer to be the same whether the NAS was acting as NUT master or was slave to another EX4100. In slave mode I doubt it can tell the difference.

I would assume that the whole point of the NAS tracking UPS status is to allow it to cleanly shut down if the battery gets too low. Having power drop in mid-operation would be bad. But I can find nothing that says:

  • If it actually does that, or it just sends an email and flashes its lights differently. (Unsatisfying if one is remote and needs to force a shutdown before it dies.)
  • Assuming it does shut down, what’s the logic for deciding when? Is it based on battery level or estimated runtime? Or on the “low” thresholds reported by the NUT master?
  • Would it respond to an explicit shutdown command from the NUT master?

I’m asking this because the NAS is a non-critical resource. If it goes offline it’s only a minor inconvenience. However, the UPS also runs my network connectivity (fiber connection, VOIP phone, and WiFi) and the NAS is the largest power consumer. I’d like it to shut down early to extend the life of more important services.

I may have to just run an experiment to see what happens. Not very satisfying, and it would take hours for the battery to drain.

And yes, bot, I’ve already filed an “incident,” 230424-000397. So far, crickets.

with only one USB cable per UPS NUT is an option for multiply NAS devices.

I just added more batteries to the UPS and more UPS systems as I did not have time to finish the Raspberry PI NUT slaves and masters

Please do test and report back

( with all the firmware updates over the last years - I wanted to not use the build in system )

If you look at the WD documentation, it would appear that the NAS doesn’t actually shut itself off, it just starts flashing its LED as red instead of blue. Not helpful if you’re, say away for the day.

I just got a call back from support. The guy obviously knew nothing about all of this. He finally figured out that yes, it was possible for things to shut themselves down if on UPS with low battery, but didn’t know of the NAS would do that. He said he’d check with Engineering.

Well, after poking around in the internals of the NAS I see that it never actually turns itself off due to low battery. If the “low battery” condition is signaled it basically quiesces itself. (Maybe “hibernate” is the right word.) No disk activity, no responding to shares, but power is still on still paying attention to UPS. If, then, it sees the UPS come back online it starts up again, presumably a quicker process the a cold start. Presumably the NAS leaves itself in a state where power loss won’t be harmful, but if that happens it will have to do a cold start when power is restored.

The only thing I haven’t figured out is how it decides that “low battery” applies. I’m guessing it waits until the UPS reports that the battery is down to its last few percent, or perhaps just a few minutes of runtime remaining. I’ll report back if support can shed any light on that.