Dual Power Supplies

[E1Designs]

If a server has dual power supplies should I plug both in to the UPS with the NMC or plug one in to that, then anotehr in to a battery backup only device, so save load on my UPS, for other items?

 

[rwullems]

Well, whatever solution you choose, keep one thing in mind, a server with 2 power supplies normally does lad balancing between the two supplies.

Meaning, if you place one on a UPS and for example the other one not, and the one NOT connected to the UPS fails, the one connected to the UPS will draw a double capacity from the UPS. So in this case you may never exceed 50% of load on the UPS, or the UPS can fail if the power goes down and the power supplies try to drain all they need from the UPS, doulbing the load on the UPS.

_____________________________________
Robert Wullems
Network Specialist
SCM/CNX/MCSA/Network+/CNA

 

[E1Designs]

I went ahead and placed them both on the same UPS, to avoid any potentiial "variables".

Thanks for the info though!!! Never knew they were load balancing...

 

[FredWagner]

To be really secure, you might want to run each power supply on a separate UPS, so if a UPS malfunctions, you don't dump your server. To protect even further back upstream, you could have each UPS on a separate mains circuit, so if a breaker pops, it only interrupts one channel. Depends on what situations calling for the UPS to kick in are most likely to occur.

Fred Wagner