A Key to Google's Data Center Efficiency: One Backup Battery Per Server


One of the geekiest, yet often obsessed-about, aspects of Google’s (s GOOG) innovations is its data centers. Up until recently, the company has been largely secretive about its data center technology and locations. But the search engine giant gave a rare glimpse today of how it’s using an on-board, lead-acid battery for each server in a data center to create a distributed backup power system. According to Google’s Ben Jai, who spoke at an event at the company’s campus this afternoon, the per-server battery system helps Google achieve an energy-efficiency rate for the backup power supply system of over 99.9 percent.

Data centers need a backup, uninterruptible power supply (UPS) so that if there’s a sudden power loss, the system can kick in until another power source (like a generator) comes online, making sure that web services don’t suffer outages. Keeping the power flowing to data centers can be crucial to a web business — a few years ago a power outage in San Francisco’s SOMA District shut down a data center, and the generators failed to come on, causing outages at web sites like Yelp, Technorati and Craigslist.

Traditional data centers have one centralized UPS room or area that starts up in the event of a power outage. The Google-designed battery-per-server setup is vastly different than the standard one and allows for a significant amount of power savings throughout the data center, in part because there are shorter connections to the backup power supply. Jai, who showed off one of the server-battery devices, said that a traditional UPS design has an efficiency of 92-95 percent, but Google can achieve close to 100 percent efficiency by using the distributed model. Jai said the distributed model is also significantly cheaper in capital costs than the centralized UPS design.

In the Q&A session after Jai’s talk, an executive from 365 Main (the company with the power outage issues we mentioned above) asked Jai and Google’s Chris Malone and Urs Hoelzle if server manufacturers had approached Google about manufacturing the on-board battery server design. Malone, Jai and Hoelzle said that Google had not pursued that as a source of revenue for the company, but that it has some patents for the on-board UPS that it might be interested in licensing. (photos of Google’s server-battery design coming shortly).


Dave Samon

Your not seeing the entire picture. A typical setup has several large industrial UPS systems (takes up space). These are then connected to the racks by PDU systems (upwards of $2,000 each, each rack would need 4 or 5 of these units to power all the servers in the rack). That cost alone would cover batteries (which by they way only need less then 3 minutes of run time..why? Because the backup generator kicks on after 30 seconds of power loss. So the batteries are not equivalent in power/ size to an industrial size unit). There is more hardware in the development of a commercial UPS setup then just a large battery (a lot more).

In all they save on the ‘infrastructure’costs, saving a ton on product (all those PDU’s), installation, maintenance (support contracts) and space (no way pdu’s will fit in those containers). Not to mention with all those rpdus you now have more devices on the network that have to be managed..and those have a failure rate as well. Plus, space is a huge issue with an industrial UPS application..they are saving space..saving on lighting etc).

Spec out a system from a UPS company to power the same amount of servers google has and you will see what I mean. It’s a matter of time before Dell and IBM ship with small 2-3 minute run time batteries in their servers (which can be monitored in the operating system easily – and integrated in to network node management software to alert when replacement is needed- this is already being done).

Subhankar Ray

At AAfter Search we have real problem with the off-the-self battery backups. They are un-reliable.

Apparently, their voltage waveform is not good enough to satisfy the servers. Hence, if there is an interruption, the server restarts even though the UPS passes all self-tests.


Subhankar, I rather suspect this was the fault of the power supplies rather than the AC waveform from the UPS (probably capacitors too small to hold up).

I’ve had this happen with the DC inverters I use as well.


Are we part of this problem??
As the bondings of google increase day by day, and to give the best possible service as the article mentions google goes with UPS(un-interrupted service) with UPS(un-interrupted supply).
So if we could remember few of our keywords and not use google search frequently for the same set of searches and start using favourite options, will the google data-centre consume less power??

Rick Cockrell

Another BS story from Google to make themselves look good. First a battery is a battery, is’t only so efficient and it’s got to be continually recharged.

Google is infamous for making themselves look green while truely hammering the enviroment. Google utilization rate on the servers usually is arround 10% so they can process data very quickly, if it were arround 70% they’d process info slower by they’d cut their energy bills dramatically. Also, they stopped cooling their servers with mechanical cooling to cut their energy. Which sounds green until you realize their failure rates on their servers will go up by 200%. Google makes their own servers so it’s cheaper but not sustainable to the planet. Look at the fact that according to the EPA we have more than 50 Million tons of e-waste that needs to be recycled (sent to china landfills) annually. If everyone took Googles approach we will soon be looking at the new Love Canal, in Palo Alto. Google needs to seriously look at themselves in the mirror.


Gizmodo did a little post on the one-battery-per-server story too: http://tinyurl.com/dc8b4h

What struck me is how much more electricity the Google data center appears to consume than a typical setup.
A rule of thumb for data center consumption is 30W/sqft… but Google has 1160 servers crammed into a shipping container (either 150sqft or 300sqft, depending on whether or not its a 20 or 40ft container). Each container uses 250kW!

For comparison and perspective, baseload power for a 10 story office building in Connecticut that I’ve done analysis for is just about 300kW.


Their savings are mainly du to the fact they don’t have to convert AC to DC and reconvert DC to AC, as it is the case for standard UPS’. The batteries are installed where DC is already existing : In the equipment.

To have distributed Batteries is not necessary Green though. DC UPS distribution with DC IT equipment would be a even better idea.

Katie Fehrenbacher

Vern, Chad, it’s real as far as I can tell and I did several interviews with the Google engineers there. Other publications are also reporting it as well.


Sorry, this sounds ridiculous to me. Knowing the vast quantity of servers Google has, the maintenance on this would be insane. The only reason Google gets away with it is that they have so many redundant servers that they don’t care if a significant number of them crash when their onboard batteries fail.

I’m also skeptical of the supposed savings. It’s the same distance to transmit the power, whether that distance is on the line side of the UPS or the load side of the UPS. I’m also sure this is not anything close to a new idea, I recall seeing a PC with an onboard battery backup at least 10 years ago.


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