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Comments: 155 +- IT: Facebook Putting Batteries On-Board Its Servers on Friday November 27, @12:59PM
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kdawson
on Friday November 27, @12:59PM
from the following-where-the-big-boys-lead dept.
from the following-where-the-big-boys-lead dept.
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1sockchuck writes "The data center of the future may have no central UPS units, and be filled with servers with on-board batteries. Facebook says it will adopt a new power distribution design that shifts the UPS and battery backup functions from the data center into the cabinet by adding a 12-volt battery to each server power supply, an approach pioneered by Google. Facebook says the move will slash its power bill and save millions in capital expenses on UPS systems and PDUs. Facebook acknowledged that these types of custom designs are limited to large companies, but called on server vendors and data center builders to adapt their offerings to make them available to smaller companies."
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On board batteries fine, but 277 volt? (Score:3, Interesting)
Why 277 volts?
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Re:On board batteries fine, but 277 volt? (Score:5, Informative)
277 (V) corresponds to the line to neutral voltage of a 480 (V), 4 wire power distribution system. 480 (V) systems are fairly common in industrial settings in the United States. The major disadvantage of using 480 (V) to power a server, is you can't use a UPS. UPS on 480 (V) systems are rare and expensive, hence the reason why Facebook wants the batteries inside the server.
I'm pretty certain you really don't want to run servers from the 277 (V) line to neutral voltage of a 480 (V), 4 wire system (3 lives, one neutral). On a 4 wire system, you have 4 wires and you can lose any one of them. If you lose the neutral, your servers could be running of 480 (V) instead of 277 (V). They will be destroyed.
Losing the neutral is a relatively common failure in 3 phase systems, as many 3 phase systems are 3 phase, 3 wire with a fake neutral/ground connection that is often mistaken for a neutral. This central connection is purely to prevent the 3-wire system from drifting off of off ground, like when lightening strikes, which is common in a big high-voltage system. When operating a 10,000 (V) to 480 (V) step down transformer (the transformers inside the metal fenced enclosures), a small amount of electric slippage to occur between the windings. 1% of 10,000 (V) is 100 (V). Faults can also occur in big loads, like motors. A 10% ground fault on a 480 (V) 400 (A) motor, could be 200 (V) at 40 (A). These voltages/powers are nothing for a 480 (V) motor, but are enough to cause significant damage in a computer with a 1.2 (V) processor. This mismatch is why you should never trust the ground/neutral connection on a high-voltage supply line. It is for safety, not for powering computer equipment, electronic equipment, and electronic motor drives. After having replaced tens of thousands of dollars of electronic motor drives, my rule is: make the supply 480 (V) 4 wire, and all the loads 480 (V) 3 wire. A 3 wire load with no neutral can withstand problems with the neutral. A 4-wire load powering electronics line-to-neutral will not withstand neutral failures.
If you are going to use 480 (V), you really want to use 480 (V) 3 wire AC (3 live wires, no neutral). If any one power circuit is lost, nothing really bad happens. Also, power semiconductors are readily available for 480 (V), because all the industrial motor drives require them. As such, your power supply will be cheaper.
Parent
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Three-Phase power is generally cheaper when you're talking megawatts, and can be used more efficiently.
Linkage:
http://en.wikipedia.org/wiki/Three-phase_electric_power [wikipedia.org]
A typical office building will use flourescent lighting based on 277 volt supply.
(note the above applies only to the United States)
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Re:On board batteries fine, but 277 volt? (Score:5, Insightful)
The wiring resistance is constant per meter (for a given cost) and increasing the voltage will reduce the amperage, while the power loss in the wiring is the multiplication of the amp times resistance, so, by increasing the voltage, the reduce the amp which in turn reduce the power loss in the transmission.
Parent
Re:On board batteries fine, but 277 volt? (Score:5, Funny)
Could you dumb it down a shade?
Parent
Re:On board batteries fine, but 277 volt? (Score:5, Insightful)
If you have bigger pick up trucks, then you need less of them to carry a set amount of goods and so there is less traffic on a road.
Parent
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Thank you :)
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Spare me your medical mumbo-jumbo. Say it in English, Doc!
This right after... (Score:4, Funny)
This right after they announced they were going public. This will definitely boost their stock price.
I think facebook has some good merit, however I am an avid anti facebook poster boy when it comes to destroying
relationships. If you thought it was easy before to hook up online and cheat on your spouse, well imagine now!!!
Girlfriend: "Hey, i got over 5000 friends online, isn't it wonderful???"
Boyfriend: "ummm...why are they all pictures of young good looking dudes wearing no shirts....?"
Girlfriend: "well that's because you can put anything on there..."
Boyfriend: "how long have you know these so called friends?"
Girlfriend: "Well not long, most are people that invited me to be their friend"
Boyfriend: "Why is this guy keep writing on your wall how hot you are....I am not sure i really like this..."
Girlfriend: "You always make such a big deal about nothing..."
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This right after they announced they were going public. This will definitely boost their stock price.
They never said they were going public, they just changed their share structure in such a way that can be construed as a precursor to an IPO.
What they did say, however, is that using those batteries will save them a lot of money.
Oh good (Score:5, Funny)
What would the world be like if facebook went offline... I'm not sure I could continue living.
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I'd notice. I'd get my wife back. I'm a Facebook widower.
It used to be me on Slashdot ignoring my wife. Now she's on Facebook ignoring me.
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What about disposal? (Score:2, Interesting)
Re:What about disposal? (Score:4, Interesting)
Those Pentium IIs are what gives me something to do... so many break/fix calls between them and the same company's over-complicated network.
My point was just that you can't assume everyone has the same refresh cycle, just like you shouldn't assume that all servers are in a datacentre, or that racks are only in a datacentre, or that all servers are on racks, etc. There's a lot of variety out there.
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maintenance nightmare (Score:2)
Since batteries have to be replaced every few years that will not be any fun taking those servers out of the racks one by one to replace their batteries. One would hope they'd be changeable from the back or front, but I wouldn't bet on it.
Also, UPSs can be retained when you buy upgraded servers. But if it's built in, you get to buy it again.
And capacity? You can't just get a bigger UPS to run longer on battery. Although if you have true external (genny) power you just need something to hold for the cuto
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I didn't replace my servers every year. I did cycle them down to lower priority uses though. :) We had some machines over 5 years old that were doing simpler lower priority tasks. There's no need to throw the equipment away every year, if you could recycle it to another use. Well, unless you have a huge budget, and like throwing money away. I always preferred to waste my budget on better stuff.
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Well, you need to take into account the full cost of ownership. Are those servers using 500W of power to run, doing 1/4th of the work of a new server requiring only 300W ? At 10c/kWh, it cost you 1500$ / year to keep them running not including the climatisation, beside the wasted space (4 times more than the newer servers), and you will not be able to sell them at a meaningfull value after too long.
"mesh" thinking (Score:3, Interesting)
The problem with mesh computing is that it doesn't save in energy costs. With a centralized UPS and power supply, improving efficiency requires that you upgrade one unit. This way, you have to upgrade a few hundred units. It's similar to why moving to electric cars is advocated despite their limited range and low performance: Because it's easier to upgrade a dozen power plants than a few hundred thousand cars, to take advantage of the latest technology.
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Unfortunately, that UPS is intrinsically less efficient. Resistive losses keep you from just provisioning 12 VDC to the racks, so you have a DC power supply feeding batteries which feed an inverter (to produce the same AC standard as the input) which then provisions power to the racks. That inverter will never be 100% efficient, nor will the power supply.
The server power supply with built-in UPS skips those two losses. The power supply already has to rectify 100-220VAC into 12VDC (or actually a bit above th
The best solution? (Score:4, Interesting)
This is interesting to me in a couple of ways.
The idea is that it is cheaper to have just a battery instead of a UPS. A UPS will also have to have an inverter.
Okay I can see this but they why have it at the server level?
Remove the power supply from the server and put it at the rack level? Have a big redundant power supply for each rack and batteries for each rack?
Or why not use DC for the entire data center and put the battery at the Data Center level?
Seems to me that there may be more than one way to skin this cat and each have it's pluses. If you are using a large number of low load balanced servers where having any one go down isn't a disaster then putting the battery on the server would give you a good trade off. You are probably more likely to have a single server to fail than a more centralized system would but the odds of taking down the system would be tiny.
I would love to see a study of the benefits of each type of system with the trade offs.
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I know my company has looked into this somewhat. Thinking about putting an inverter at the rack level and supply DC power to all of the systems on the rack (we make hardware). This would move the power supplies out of individual system to the rack.
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Or why not use DC for the entire data center and put the battery at the Data Center level?
12VDC, each unit needs 300W at least... That's 25 amps per unit. Think wire gauge [windsun.com]. That's the reason, long and short. That, and you can't run 12VDC very far before power loss becomes a significant consideration.
Tesla figured this out over a hundred years ago -- AC powers and transformers = more efficient.
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Actually they run DC data centers at telco voltage levels which is a believe 48 volts. Since you are only sending power hundreds of feet and not miles the losses and wire gauge involved are not that bad. Now if you put the put the power supply at the rack level then you could run 12 volt to the servers.
BTW phone exchanges traditionally ran on 48 volt DC so those systems are mature to say the least.
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If you read the Google stuff, they have a number of reasons for it. Firstly, they wanted to minimize or eliminate conversion costs (Converting AC to DC and vice versa takes energy, sometimes 10-20% right off the top in heat. Secondly, they didn't want to have to do standard systems planning to deploy more capacity. With a central UPS, you have to worry about how many systems are plugged in, how many VA, etc. You have to do these calcuations and planning all the time with new hardware configurations. Go
New wheels, same cycle.... (Score:4, Insightful)
Distributed!
Centralized!
Distributed!
Centralized!
Distr...
ad infinitum
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Thanks a lot, guys... Now I lost my train of thought!
I'm sure this looks great on Powerpoint (Score:5, Interesting)
Facebook says the move will slash its power bill and save millions in capital expenses on UPS systems and PDUs.
And it'll move the complexity and unreliability to the server. The whole idea behind centralized UPS's (and by the way, you still need PDUs) is that you have reliability, serviceability, and economies of scale and efficiency. Now you have to monitor and service the batteries in thousands of pieces of equipment. And guess what happens when one of those batteries fails by getting cooked? Sulfuric acid all over the place (yes, even the "sealed" lead acid batteries can fail and leak) instead of the batteries being in, say, a battery room. God help us if they use lithium-ion, which would introduce us to a world of server fires and water damage, since a lot of datacenters are now dry-pipe to save costs. Nevermind that batteries and their associated electronics take up space, and that space has to come from somewhere.
So, now you have each server getting more expensive, more complex with both hardware and software (server now needs its own battery power management) heavier, bigger, featuring toxic materials, and now non-standard, non-commodity design which vendors will charge more for as they specialize the equipment.
I'm sure this all looks great on a powerpoint slide simplified into "if we put batteries in our servers, we can throw out our expensive UPS and save money!" This is just another hot/stupid trend; just because Google is doing it, doesn't make it brilliant. I stopped believing everything google was doing was a Best Practice around the same time gmail started going down for hours (and for some users, more than a day) at a time on a regular basis. [google.com]
I tuned out of the article around the point where the guy from Facebook complains about cosmetic features interfering with airflow. Uh, guess what, bud? Dell's pretty front panel has been optional (saving you a few bucks sometimes) for years.
Re:I'm sure this looks great on Powerpoint (Score:4, Informative)
Another idea behind a UPS is _a_single_point_of_failure_. Moving the power backups to the individual servers eliminates that worry. Plus, since the servers are already redundant, you don't need the redundancy on the UPS, inverters, etc., which should save money.
And since it's long-term, I'm willing to wager it won't be lead-acid, but NiMH. So no real maintenance issues. And your "what happens if..." scenarios apply equally to a battery in a megawatt UPS or a battery in a server.
As for battery management and 'specialized' power supplies, etc.: go check out a laptop. That wheel has already been invented, and better yet, has benefitted from mass-production.
Parent
I'd like to see more servers that can reduce power (Score:2)
Most servers sit there at 3% cpu until something strenuous occurs. You've still got the big fans blowing, drives spinning like mad, and lots of power getting sucked down. I'd like to be able to see these units able to reduce power in low-use times and seamlessly ramp up when demand hits. It bugs me that we leave servers running overnight at full clip simply because we don't want to come in early to turn them on for the early workers, don't trust they'll come back on after a powerdown due to IT voodoo, etc.
Facebook is converting to solid state drives. (Score:3, Interesting)
Facebook is also converting over to solid state drives. They will have relatively low power consumption per board. Putting both flash chips and a backup battery on each board makes sense.
Why? (Score:2)
This is idiotic. Why not just run the equipment on 48VDC (telco style) with extremely high efficiency DC SMPSes and heavy gauge wiring? Power that directly with a large bank of batteries.. no inverter.. no distributed battery mess (pressure discs do burst).. no capacity limits.. no server weight issues..
Not to mention, under this scheme you can no longer fully de-energize the datacenter (or parts of it). An EPO switch could cut the mains, but I certainly wouldn't want thousands of fully-charged batteries
This may be a better solution than a regular UPS (Score:4, Informative)
I used to work at a company that decided to install large, monolithic UPS systems after the power company hit them with a spike that took the entire system down for over a half hour. As they're a broadcasting company, they (rightly) felt that feeding their network affiliates nothing was not a good idea.
As a result, they have these UPS "rooms" that hum like the dickens when you're passing them in the hall, all with batteries that will need to be replaced regularly (just like the Google server battery systems, so it's the same problem no matter what). Reason for the hum?
The hum is caused by these giant transformers that step the power from DC to AC and create 110 volts of AC current at whatever amperage is required for normal devices. But there is a lot of wasted energy in doing that.
Computers and servers all run off of DC power. They plug into AC power and then run that AC through a "power supply" that converts that to DC that the computer can use. That takes power, but power is plentiful when it comes from the power company and you pay your bill on time. But when you take the power from the power company, then change it to DC to charge batteries and then take power from those batteries to change it to AC to power normal wall outlets only to take that through a server's power supply to change it to DC again for the computer to use it, you're looking at lots of wasted energy in just changing from AC to DC, back and then back again, as well as changing to the kind of voltage and amperage needed to run the microprocessor, power the memory and power the drive arrays.
So this is all about lowering consumption. And if you lower consumption, you lower your electricity costs.
The hobbyist magazines were all aflutter some years ago about using photovoltaic (solar) energy to power a house. But what everyone had to do (early on) was to change their appliances (or order special ones) to run on DC -- not because you couldn't make AC current from the DC output of the photovoltaic systems but because it took a lot of energy to do that and these hobbyists were all about trying to save so much energy that they could take themselves off the grid.
Here, on a large scale, you see the same idea. It's just more efficient to do this. And one of the big arguments in the early years of electrification was between DC power distribution (Thomas Edison) and AC power distribution (George Westinghouse and Nikola Tesla). We may wind up fighting these battles again in the near future.
routers/switches? (Score:2)
Don't they require power too? It's all very well keeping your server up in the event of a power failure but unless you keep your routers (and the routers all the way to the backbone) up, what's the point?
Why is this limited to big institutions? (Score:3, Interesting)
The point being that it's dumb that a UPS has to invert the power coming out of it just so the power supply can rectify it back to DC. I'd much prefer saving the step and running DC straight from the UPS to the motherboard.
Come to think of it, the standard isn't necessary, a UPS manufacturer could do this today, although they would have to bundle the dummy power supply with the UPS. The cost could even be kept somewhat reasonable if you factor in the savings from not having to buy a power supply. The only major sticking point is that most UPS vendors put out a lot of distressingly bad products and the consumer trust issue will be a problem.
Makes even more sense in SOHO and Retail (Score:2)
I remember seeing a power supply around 2004 that had one or more backup batteries that fit in trays in 5.25" drivebays so you could hot-swap them and they were internal to the server. A SOHO or retail server (for a handful of POS' ) with this and a couple of PCI multiport ethernet cards and a PCI docsis or DSL modem would do a lot to consolidate the IT equiplent and all it's power bricks and interconnections. Sadly I've not been able to find that type of power supply since.
Doing it wrong.... (Score:2)
Yes, computers operate on DC.
Yes, putting a DC battery in between the DC output of the PSU and the DC input of the mobo will have a UPS / Laptop battery effect on temporary mains voltage loss.
The problem is very few mobos only have 12VDC input. This won't take care of the vast majority of mobos that also require 5VDC
5VDC isn't practicably doable from lead-acid @ around 2 VDC per cell.
Yes, there are ways around this, but the only practical ones are external DC-DC conversion, *or* 12VDC only mobos, which use
Re:12 Volt? (Score:5, Informative)
Since when is 12 Volts a measure of battery life? You still need to know how many Amp-Hours the battery can provide and the power usage of the server.
You could have a 100Amp-Hour 12 volt battery, or a 1Amp-Hour 12 volt battery...
Parent
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That's a great answer. :)
I have an RV that uses "Group 8D" batteries. They're 12V, 1200Ah. Unfortunately for this discussion, they're also about 150 pounds, and over 4u tall.
The batteries that I saw in the Google machines were pretty small. They were probably enough, as the GP said, to keep the machine long enough to shut it down safely. I suppose they may be enough to provide power until the generators kick on, but that wouldn't leave a lot of margin for er
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Small personnal UPS usually gets 2 12V battery at 8AH to 12AH. In a server environment using the google way (cheap quad core), the computers are probably using under 200W (no video card) and probably around 100W avg. (no hard drives everything by lan?). a 12V 8AH battery can provide 96W for an hour, less the convertion rate, so it`s more than is required to put the generators online.
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Car batteries are 12 volts, you can run a laptop on one for a long time.
Wouldn't want to carry it, though.
units (Score:3, Informative)
How long is twelve volts going to keep a server running? A UPS would guarantee that you have enough time to finish transfers and close connections before shutting down into a safe mode, even give clients a warning before shutting down.
Volts are a measure of electrical potential, not capacity. You mean watt-hours, most likely.
How long is twelve volts going to keep a server running? A UPS would guarantee that you have enough time to finish transfers and close connections before shutting down into a saf
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The VCORE might be 1.5 or 1.7 or whatever volts, but the interface signals can be a mix of 3.3 and 5 volt. A modern CPU may require all voltages to be supplied externally, or may generate everything from a single 3.3V or 5V supply, depending on the application.
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Why do you assume that the in-server batteries will be completely ignored but a central UPS will be meticulously maintained?