[Beowulf] Re:UPS system for Linux cluster

[David Mathog]

vlad at geociencias.unam.mx wrote:
 
> 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.

Do you really need a UPS for the whole cluster?

In many instances it is good enough to put a UPS on the master node and
just use surge suppressors on the compute nodes.  The up side being that
only a small and relatively inexpensive UPS is required.  The down side
being of course that any power failure will break ongoing calculations.
 However, if your work can be check pointed a power failure will only
wipe out the work since the last check point.  If your power is
reasonably reliable, this is a reasonable way to save a lot of money.
Also, unless you are also buying a generator, a whole cluster UPS will
only buy you limited up time during a power failure, so you may well
lose the calculation  despite the large UPS.

Regards,

David Mathog
mathog at caltech.edu
Manager, Sequence Analysis Facility, Biology Division, Caltech