On Sat, Jul 02, 2011 at 10:45:13AM -0400, Robert Heller wrote:
> At Sat, 02 Jul 2011 15:42:38 +0200 CentOS mailing list <centos@xxxxxxxxxx> wrote:
>
> >
> > Jason Pyeron wrote:
> >
> > >> Could you (or anyone) suggest a cheap UPS?
> > >> This is only a tiny server (HP MicroServer) on a home LAN.
> > >
> > > http://www.amazon.com/APC-Back-UPS-shutdown-software-UPS-
> > BE350G/dp/B001985SWW/
> >
> > Thanks, I'll look into that.
> >
> > >> I'm sure you are right, as I know nothing at all about power supplies.
> > >> But surely computers actually use DC,
> > >> so couldn't my torch-battery device just supply the PC
> > >> components directly?
> >
> > > You will either need many different batteries for the different voltages
> > > (1.2, 3.3, 5, 12, -12, -5) or a DC ATX power supply (not cheap and not
> > > very powerful until the 48V input variety)
> >
> > Surely one 12v battery would do?
>
> Actually not. You need both positive and negative voltages. You cannot
> just use a 12v battery with a voltage divider resistor network. And
> because the voltages needed have to be precise, you really need a
> properly regulated power supply. Like Jason said, it would be a 48VDC
> input unit and will cost you many times what a cheap UPS would cost.
>
> > It is only meant to last for 30 seconds or so,
> > so wouldn't reducing the voltage be easy enough?
> > I repeat that I don't know what I'm talking about ...
> >
>
I believe Google runs bazillions of servers with a PS that emits 12 v,
a 12v battery on the downstream side of the PS, and a custom motherboard
that requires only 12V input. If not exactly those specs, at least that
sort of thing. But Google uses so many tens of thousands of 'em that it
is economical for them to have them custom-made, whereas you want one,
so it'd cost you a fortune. (there have been a few articles on various
web sites over the last year or two showing Google's server internals.)
So, in theory you could do something akin to what you ask, but in
practice it would be much cheaper for you to spend a few bucks for a
low-spec UPS unit. assuming the server has no peripherals that require
power (such as a monitor) and it is a low-power device like a micro-ATX
board with an Atom processor, or someting of that ilk, a small-ish UPS
would work fine. Such low-spec UPS units are inexpensive.
--
---- Fred Smith -- fredex@xxxxxxxxxxxxxxxxxxxxxx -----------------------------
"For him who is able to keep you from falling and to present you before his
glorious presence without fault and with great joy--to the only God our Savior
be glory, majesty, power and authority, through Jesus Christ our Lord, before
all ages, now and forevermore! Amen."
----------------------------- Jude 1:24,25 (niv) -----------------------------
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