[Beowulf] UPS system for Linux cluster

Gus Correa gus at ldeo.columbia.edu
Thu Apr 30 09:21:27 PDT 2009

Hi Vlad

A less convenient alternative is to use a few/several smaller
rackmount UPSs, and split the cluster load across them.
They are available in 6-10kVA range from many brands,
single phase input (maybe three-phase also), typically in 3U units.
If you have a site generator, you may not need a lot of battery time,
which is our case here.
The bad news is that rackmount UPSs take a lot of rack space,
and if you need many it may not be cost effective.
We had to (reluctantly) use this solution, which I hope is temporary,
because our site large UPSs were maxed out.

Previous discussions that may be of interest:


Gus Correa
Gustavo Correa
Lamont-Doherty Earth Observatory - Columbia University
Palisades, NY, 10964-8000 - USA

Tom Pierce wrote:
> Dear Vlad,
> I did a similar project last fall. The only unpleasant surprise is
> that most UPS are capable of running continuously at 80% of their kVA
> value.   So you may want a larger system.
> You can get more current when you go to a three phase UPS system.
> On Wed, Apr 29, 2009 at 7:46 AM,  <vlad at geociencias.unam.mx> wrote:
>> Hi,
>> I have a linux cluster and need to purchase a UPS system.
>> The total expected current consumption will be 240 amps. At 120 V this
>> would require a 30 kVA UPS system.
>> However, I see that 30 kVA systems have a limitation for the input
>> current. For example, this 30 kVA system
>> (http://www.provantage.com/tripp-lite-su30k3-3xr5~7TRPL1Q9.htm) allows
>> only 90 amps as input
>> current. I am a bit confused here, and I need some advice on what UPS
>> system I should look for.
>> Thanks,
>> Vlad
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