
How a Battery Cut Microsoft Datacenter Costs by a Quarter - victorbojica
http://www.theplatform.net/2015/03/13/how-this-battery-cut-microsoft-datacenter-costs-by-a-quarter/
======
stephengillie
> _In a typical UPS backup scenario in a normal datacenter, the incoming power
> is converted from AC to DC so the battery can be charged, then converted
> back to AC coming out of the battery to be distributed out to the power
> distribution units, where it is stepped down to the 120 volts where the
> servers consume it. By putting the batteries in the servers, Microsoft can
> do one AC to DC conversion and distribute 380 volts DC directly to the Open
> Cloud Server power supplies and then step it down to 12 volts for the server
> and storage nodes._

This is a huge point of efficiency that's been missed for a very long time,
mostly because it's right along the border between the datacenter provider and
the server customer. The datacenter traditionally agrees to provide filtered
120/240v AC.

Converting the power loses efficiency. And we convert the power 4 times. They
may be regaining about a 6.25% loss from each conversion, my math is probably
incorrect.

Of course, all parties could agree to change the standard, and provide clean,
filtered 12V DC to servers, and redesign PSUs to accept this input instead.
But then they wouldn't be wall-pluggable anymore.

~~~
convivialdingo
There already is a DC standard, it's for telecom and it uses 48V. You can buy
PSU's off the shelf for many systems.

48V is better than 12 because the wiring gauge is smaller and line loss is
more efficient.

~~~
Scoundreller
-48V.

I'm trying to find out why negative is used, but the answers seem to vary a
lot...

~~~
btgeekboy
I've always been under the impression it was corrosion related.

~~~
c22
This is my understanding as well. I believe the effect is called cathodic
protection[1].

[1]
[https://en.wikipedia.org/wiki/Cathodic_protection](https://en.wikipedia.org/wiki/Cathodic_protection)

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skywhopper
I remember reading about Google doing this years ago. I've been disappointed
ever since that Dell et al haven't adopted a similar option for their
commodity hardware.

~~~
GauntletWizard
I worked for an enterprise hardware company in the 2010 era whose secret sauce
involves doing such, albeit on a more local scale. When I joined Google, they
were doing this all over. Facebook is doing this, at the rack level. Microsoft
is touting their six years behind technology, and the scary thing is, they're
still five years ahead of the rest of the industry.

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omgtehlion
Slightly off-topic: in one gig we are running buildfarm and CI on dozens of
cheap notebooks (mostly ACER and Lenovo). And enjoying this effect of local
power backup, which is very useful in our office building, because power is
very unstable. When power goes down usual rack-mounted server might work tens
of minutes off a UPS supply while these little bastards work for a couple of
hours more, just slightly slower.

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pedrocr
Hasn't Google been doing this for a very long time?

~~~
ChuckMcM
Yes, it was one of their "secret sauce" things that they kept top secret for a
long time. Fundamentally, if you change the question from "putting computers
into data centers" to "how can I build a building sized computer?" it changes
the way you think. Microsoft has been somewhat late to that particular party,
both Facebook (perhaps with some Google knowledge "leakage") and Amazon have
done a good job of internalizing this view point.

It scares the crap out of data center providers because they know they can't
really innovate like this effectively. I tried to get Equinex to consider
building Open Compute racks in a different style of co-location setup but
never got anywhere with them.

~~~
GauntletWizard
Google was in this particular paradigm well before Facebook, and I'm fairly
certain I know precisely who was involved in leaking the knowledge.

~~~
ChuckMcM
A lot of engineers have passed through Google. The interesting thing about the
Bay Area at least as this sort of porous sponge works both ways, people come
from competitors, people go too competitors, they all carry a point of view
and their own view on solving the problems at hand.

I am fortunate that I spent a few years in the platforms group and got a good
look at how Google did what they did, and with that perspective have watched
ideas in data center design emerge and flow. As the article points out Google
does publish interesting bits of data, which lead to certain conclusions. And
many of the same things that drove Google to do what it did, become the more
likely answer when you own the entire data center (or better yet build it from
scratch). I sat through a presentation of the big Ebay data center project in
Utah and noted how they were coming up with the same answers to some of the
same problems.

Because of that I doubt any one person is largely responsible there. There
seems to have been a lot of cross pollination.

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powertower
So the function is for 4 of those batteries to run the power supply for 1
minute?

~~~
duskwuff
Yep. After a minute or so, either the datacenter's backup generators have
started, or something has gone _seriously_ wrong and power won't be restored
for quite a while.

------
smartbit
video [http://youtu.be/31dwMAg-Hx4?t=330](http://youtu.be/31dwMAg-Hx4?t=330)

slides [http://www.opencompute.org/assets/OCP-Summit-V-
Slides/Mainst...](http://www.opencompute.org/assets/OCP-Summit-V-
Slides/Mainstage/OCP-MSFT-Kushagra.pdf)

specs
[http://www.opencompute.org/wiki/Server/SpecsAndDesigns#Speci...](http://www.opencompute.org/wiki/Server/SpecsAndDesigns#Specifications_heading_to_the_IC)

 _The LES shall provide sufficient ride through capacity to maintain proper
PSU output for 35 seconds (+ /\- 500ms) minimum plus walk-in period of no less
than 10 seconds (+/\- 500ms). The power supply shall meet the reliability and
operating life with drop outs at a maximum power of 1600W for 5 seconds then
reducing to 1425W for the remainder of the drop out. The power supply shall be
capable of operating at greater than 1425W to 1600W continuous drop out but
reliability and operating life of the battery are not guaranteed._

------
mark-r
3 questions: 1\. What's the lifetime of an individual battery? 2\. Are the
batteries replaceable? 3\. Will we ever see this tech in consumer level PC
power supplies? If we did, would it be of any use in an environment without
backup generators?

~~~
rtkwe
1.) Judging from their cost graph [0] it seems to be about 3-4 (definitely
less than 5). I'm guessing that the points where the costs increase is due to
batteries wearing out and having to be replaced.

2.) Probably? The cost bumps in 1 don't make much sense otherwise.

3.) Hard to tell, in a home system there isn't such a huge cost savings to be
had with a battery. As for usefulness it's a really short term battery but
it'd be good enough to let the system power-down/suspend gracefully instead of
losing power immediately. That niche is pretty well served by UPSs for people
who care though and everyone else doesn't care already. It might find a small
niche for consumers but it won't be ubiquitous.

[0] [http://www.theplatform.net/wp-
content/uploads/2015/03/open-c...](http://www.theplatform.net/wp-
content/uploads/2015/03/open-compute-microsoft-les-benefits.jpg)

~~~
mark-r
Now that I think about it, a power supply that held power just long enough to
go into hibernation automatically would be very useful. There would need to be
some signalling into the OS though.

~~~
MertsA
We already have support for this in every OS, it's no different than a laptop
or existing UPSs. What sucks is that to work with a generic ATX motherboard
without a special header to hook into the best externally accessible bus to
put it on is probably going to be USB. It's not like you would need to plug it
in outside the case either, there's usually a spare USB header anyways.

But hypothetically, APC could make an ATX UPS today that would be compatible
with most ATX motherboards and leverage most of their existing software and
drivers to do so.

~~~
mark-r
I just worked on a PC this weekend, and all the internal USB connectors went
to sockets on the front panel. But it should be possible to put a socket on
the back of the power supply and include a 1 foot cable. This is doable!

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dfc
I do not understand the new dupe detection system. The same user posted the
same link 10 hours ago:
[https://news.ycombinator.com/item?id=10368978](https://news.ycombinator.com/item?id=10368978)

~~~
Jtsummers
When there wasn't uptake on an interesting article the mods contact the
original poster and ask them to repost it.

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mockery
$0.25 doesn't really seem like that much of a savings...

~~~
user_0001
:-)

