This is a weird thing I have happening on one of my servers, these have been running nearly 7-8 years but I recently swapped a new MB/CPU etc in a server. IT’s SC836 dual redundant PSU.
So both PSU are plugged in it’s own UPS. When I pull the plug from the wall, the PSU that’s on battery will go yellow and scream loud alarm. Mind you other servers are connected to this UPS getting battery powered AC. Only this server does this. I tried it with both PSU and both do the same thing. Is something wrong with the chassis PDU/PMBUS or something else like MB/ram/CPU?
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Is your UPS a stepped sine wave or a true sine wave?
Does the alarm go away if you completely unplug the other PSU? Does the server keep running if you do or does it shut down?
Simulated sine wave. The weird thing is my 2 other supermicro servers on those UPS don’t have that issue, it’s just this one.
The alarm is normal, if you unplug 1 PSU it warns that something is wrong. But it shouldn’t do that on UPS battery. Server keeps running because other PSU supplies power to server.
Some systems don’t like simulated sine waves.
You need to test what happens if you unplug the second PSU because it’s possible the first is shutting down on what it considers an invalid input. You might not actually have any redundancy.
Both PSU do the same though. It’s not specifically one of them. Whichever ups I put on battery, the PSU will act like it’s not getting power.
I get that it happens with both. What I’m telling you to do is to put one on battery and completely kill the power to the other.
If the PSUs are alerting because they don’t like your budget UPS but they still work then fine, that’s annoying. If they’re shutting down because they REALLY don’t like it then the UPSs aren’t doing anything aside from making your setup less efficient and you don’t actually have any backup during a power loss.
Yeah it kills the server. The one on battery doesn’t sustain anything. The UPS is not giving any backup power for black/brown outs for that particular server regardless now.
Is this really just PSU? Or it’s tied into the MB somehow?
Assuming this isn’t user error, where you have your Server plugged into outlets that are only surge protected and not battery powered, you have it backwards. Your server, or more specifically the power supplies, power controller, and the BMC (if you have one), aren’t DRAWING any power from your UPS because they don’t consider it clean enough to use. The UPS doesn’t “give” anything.
Check to make sure you’re using ports that are powered under battery and if so your options are to get a new UPS that generates a pure sine wave, get a new server that doesn’t care, or just plug it straight into the wall and know that it will shut down during a power outage.