David Mathog wrote:
v...@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
Another reason for not having UPS power for an entire cluster is
cooling. In our server room, if we lose regular power, we lose our
large AC units as well. So we need to be careful what we keep plugged
into our emergency power circuits (a relatively tiny amount of
equipment). Having an entire stack of nodes churning away during a
power outage would kill us pretty quickly.
- John
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