Which UPS for two server?

Robert D. Holtz - Lists robert.d.holtz at gmail.com
Thu Dec 21 06:31:05 CST 2006

> My concern is about redundant power suppliers. I think that during 
> normal operations, only one of them is actually working, and in case the 
> first breaks, the second takes over the faulty one and stars working. 
> What is going to happen in the switching moment? Will I have a current 
> spike?

The power supplies run in active/active mode, i.e., they're both feeding
power to the system.  There is no switch period.  On failure more current
starts flowing through the one that's still okay.

> My question is: which is the best (in terms of available power) 
> rack-mounting UPS that I can buy to serve these two babies?
> If the total power is 1420W, I could go for the APC Smart-UPS 3000i, 
> 2700 watt (probably the APC Smart-UPS 2200i, 1600 watt is enough, but 
> the load will be tight to 100%). What about the current spike I 
> mentioned before?

Buy two APC rack mount units.  Model is your preference of features.  Take
one power supply from each server and feed it from the first UPS and take
the second power supply from each server and feed them from the second UPS.

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