[CentOS] Power-outage

[Robert Heller]

At Sat, 2 Jul 2011 18:10:09 +0100 CentOS mailing list <centos at centos.org> wrote:

> 
> On Saturday 02 July 2011 15:45:11 Robert Heller wrote:
> > At Sat, 02 Jul 2011 14:52:27 +0200 CentOS mailing list <centos at centos.org> 
> wrote:
> > > Emmanuel Noobadmin wrote:
> > > >> It seems to me that it should be possible
> > > >> to have a simple, torch-battery operated, system
> > > >> which will keep the machine alive long enough
> > > >> to make a graceful exit.
> > > > 
> > > > The problem
> > > > with your idea is that you'll need a DC to AC inverter that can handle
> > > > the output current required by your server and something to hold the
> > > > batteries (you'll need more than one because attempting to draw a huge
> > > > current from a normal battery will either kill it or at the very least
> > > > cause it to have a shorter than expected capacity) and everything
> > > > together, it's probably going to cost more in both money and time to
> > > > have this thing.
> > > 
> > > 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?
> > 
> > A PC uses several *different* DC voltages: +12, +5, +3.3, and several
> > others and they need to be *precise*.  Some of these are not an exact
> > multiples of the standard 1.5V Carbon-Zinc cells typicaly used in torch
> > batteries.
> 
> I wonder, how is this issue solved in laptops? They use only one DC battery, 
> typically with a single voltage output, AFAIK.

*Mobile* processors don't use as many voltages.  You will note that
laptop disks use a single 5V for power, as opposed to the 5V (logic) and
12V (motor) power a desktop or server disk drive uses.

Laptops also use DC-DC power converters to get the addition *few*
volatages needed (eg 12 => 5V and 3.3V).

(I'm guessing that Google's massive array of battery powered servers use
things like Atom processors or some other mobile or embeded processing
elements on their custom motherboards, which might be a customized
variant of a laptop or embedded processing motherboard.)

> 
> Best, :-)
> Marko
> 
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>                                                                                                                  

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Robert Heller             -- 978-544-6933 / heller at deepsoft.com
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