OT: UPS for FreeBSD

Perry Hutchison perryh at pluto.rain.com
Tue Dec 2 08:22:01 UTC 2014

Alejandro Imass <aimass at yabarana.com> wrote:

> ... at high power you would still need to employ high voltage to
> decrease loss in the distribution, or you would need to employ
> ridiculously large conductor bars to be able to distribute
> low-voltage DC even in the most modest data center ...

Oh, for Pete's sake!  What part of "integrate a UPS with the PSU"
is so hard to understand?

I'm proposing that the individual PSUs be designed in such a way
that a battery or two can be connected into each PSU, between the
rectifier and the regulator.  The cables between the PSU and its
batteries would be maybe a foot long (if the batteries are mounted
adjacent to the server, say in the next rack slot above or below)
-- or up to a couple of meters long if all the batteries were housed
in the bottom part of the rack with all the servers above -- and the
conductors would not need to be much (if any) heavier than those
connecting the regulator outputs to the circuit boards.

Of course, if one insists on serving a whole data center (or even
just one full server rack) from a _single_ UPS, that UPS is going
to be a massive piece of equipment and the power distribution to
its loads is going to require infrastructure commensurate with the
amount of power involved.  (It's also not all that reliable an
arrangement, since the UPS becomes a single point of failure capable
of taking down many systems.)

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