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Is it possible to run a dual power supply server with one PS plugged into 110V, and the other power supply plugged into 208V? We've asked the vendors and they say they've never tested it or some other "i dunno" type of answer. The power supplies both work at 110 and 208 without any issue, it's the 'mixed' operation that is in question.

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This has been discussed a few times previously. It will probably work. You will probably be fine. If your case falls outside the "probably" envelope (and there's no real way of knowing) VERY BAD THINGS could happen. Procedure is not recommended. –  voretaq7 Jun 28 '11 at 16:56
    
No (in my test). I just tried something similar with HP server with 2 different PSUs - a 240VAC PSU and a 48VDC PSU - it complained on boot and I had to take one out.. –  xcxc May 7 at 4:07

3 Answers 3

It almost certain will actually work yes, doesn't mean it's a smart idea however - do don't do this please.

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Thats up to the server vendor. If you don't even tell us, which servertype you use, nobody could you answer this.

It should work, as the supplies will output the prober voltage anyway. But maybe the server's monitoring chipset don't likes that.

EDIT As you really need the mixed-operation you should test it with an old/broken system first. If there is no trouble, you have a great chance the other systems will stay alive. Keep the mixed-operation as short as possible, but long enough to allow the supplies to make a failover.

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When playing with voltages like that, and given that vendors don't know the effect of doing it, I'd highly recommend not doing it if for no other reason than we're talking about servers, not fireworks. –  Bart Silverstrim Jun 28 '11 at 17:40
    
Currently moving a datacenter from 110V to 208V... being able to hot move the servers without outages would be nice to be able to do. Mostly a mix of Dell poweredge and Cisco Nexus 22xx/50xx equipment, with a small number of HP servers as well. –  Nathan Neulinger Jun 29 '11 at 17:55

Obviously, I have to disclaim any liability for if something happens.

That being said, running them on two different voltages is no different than running them on two different 120v circuits. The power supplies transform the power to uniform outputs, so the only issues that you could run across are things like differing ground references, power factor differences, etc.--the same types of problems that can come up with from different circuits of the same voltage.

Although this is possible, it's not necessarily helpful; with 208, you are using two hot legs of a three-phase, 120v system. In other words, you are doubling your risk exposure versus using only one: if either hot leg fails on the 208, you're down. If your building also had a 277/480 service, that would provide a higher level of reliability, since they are different services (different transformer, feeders, and gear/switching).

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It's to allow us to move to 208V without taking outage on the server, though obviously, you're right on the exposure, though from what I understand, with the loading we have, if we lost a leg, we're pretty much SOL regardless. –  Nathan Neulinger Jun 29 '11 at 17:57

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