[ale] [OT]Random wonderings

[Lightner, Jeff]

Back when I first started doing systems it was common for every rack to
have a UPS in it and all the systems in the rack plugged into that.

Over time however, most data centers have UPS that covers the entire
room and a generator.   The idea is if you lose power from the grid then
you run on generator.   Everything runs off the data center UPS to avoid
surges etc... (especially when switching from grid to generator).  If
for some reason the generator doesn't work the data center UPS will also
allow you time to power down things in an ordered fashion. 

Weight is definitely a consideration, so is space - having just a UPS in
every rack took up valuable rack space.   If every server had to
accommodate room for a UPS built in they would take up even more space
in the rack.

It is news to me that all data centers are moving to DC power.   I'd
think that would be the exception rather than the rule.   One would have
to buy systems that allowed for DC input rather than AC.   Not a
technological challenge since internally most systems convert to DC but
I haven't seen a lot of systems that allow for DC input.   But then
again I haven't really looked into it.

-----Original Message-----
From: ale-bounces at ale.org [mailto:ale-bounces at ale.org] On Behalf Of Tom
Freeman
Sent: Sunday, April 10, 2011 8:20 AM
To: ale at ale.org
Subject: [ale] [OT]Random wonderings


I needed to bring a machine back up and recommission it yesterday. A few

random thoughts occured to me which I thought I'd toss out. Nothing
really 
commercial, but a DIY might blaze a trail.

Big thing was, why do we put up with a separate UPS  for a desktop style

computer? Although not cheaper, moving the UPS components into the
system 
case could eliminate a cord or two, help with the housekeeping by
reducing 
the exposed "thing" count, and encourage better power for the equipment.

Of course, I've never seen such a thing offered commercially, and I'm
sure 
I'm overlooking something important. I do know that thermal management
is 
a potiential headache. Simple overall weight is another. How big those
two 
issues are I just don't know.

Of course, there could also be advantages to such a scheme. Aren't some 
data centers switching to DC power, which is little more than battery 
power. Such a change might (maybe?) improve the power efficiency just a 
mite also although the improvement would be pretty minor.

Another idea, probably born of ignorance, is why are consumer UPS's
setup 
with just one battery? OK, the UPS can be built for a pretty hefty 
battery, but still. Why cann't the end user drop in another battery to 
extend run times? Are the circuits that much different? I am assuming 
maintaining the same peak current draw here.

In fact, are we actually limited to just batteries in our UPS's? Both 
graphite flywheels and super capacitors appear to have longer lifetimes 
with similar levels of care as the modern lead acid battery. Plus less 
hazardous disposal procedures.

Last psychotic thought. Is there a nonX-86 derived motherboard out there

suitable for desktop/server use? One with the power levels of some of
the 
embeded chips, but with memory expansion and access to the bus and 
periferal (sp?) boards? I cann't remember such since about 1996 and the 
Rebel line of servers.

I'm probably missing something important at each point here. Education 
will be welcomed.
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