Dual PSU's - connect both to UPS?

[sidewinder]

All our servers have dual redundant hot swap PSU's

 

Until now Ive always plugged one into the UPS and one into the wall. This did seem sensible

 

But now I think about it, it seems stupid. Surely any protection you're getting from the UPS from power surges etc, you're losing by having the other one plugged into the wall? So you could still well get a fried motherboard

 

Am I right in thinking this?

 

If I am, wont having both PSU's connected to the UPS draw double the power and seo need more UPS's/higher capacity? Or does one always draw only a small amount until it is called upon?

[Geoff]

Plug both into your UPS.

The server only uses one PSU at any one time.

If you do anything stupid, hopefully the UPS will complain rather than explode.

[DMcCoy]

unless you overload it. In which case it will just turn off.

 

Oh, and powerchute defaults to "switch the ups off after shutdown"

[Halfmad]

Definately plug both in!

[robknowles]

Hello,

 

I would either

 

a) Plug one into a UPS and the other into the mains (via a surge protector)

b) Plug each power lead into two different UPS

 

I recommend this because a couple of summers ago (on the exam results download day) I had a UPS suddenly die and having both leads in meant the 5 servers connected to it went straight down, so plugging into two different devices would add redundancy.

 

Rob

[StewartKnight]

I second Rob, if only one PSU is going to work anyway, then only plug one into the UPS!

[Ric_]

If you are bothered enough to have redundant PSUs you should really splash out on a second UPS and plug one supply into each.

[sidewinder]

I have got a second UPS, its an older floor standing one but its good enough. Also got some smaller APC rackmount ones lying around so should be OK

 

Will do that over half term then

[maniac]

We have 2 UPS's and our servers that have duel PSUs have one plugged into each UPS.

 

It's not just the surge protection and battry backup a UPS provides, but it also adjusts the voltage to give a precise 230v AC and adjusts the frequency to give a precise 50Hz. Therefore the transformers and electronics inside a computer PSU will function more accurately when running on a UPS becasue the input power is much more precise and consistant. OK it's only maginal, but it helps!

 

Mike.