Feeds

Facebook beats the heat in North Carolina data center

It's not the heat or the humidity

High performance access to file storage

The techies at Facebook may like to "move fast and break things" as company founder Mark Zuckerberg admonished them to do three years ago before the social media juggernaut went public, but the one thing they don't want to do is break a data center and all of the servers and storage running inside of it.

But using outdoor air cooling in its Forest City, North Carolina data center, which started serving up applications using the company's custom and open sourced data center designs in April, was a tad bit risky.

Daniel Lee, a mechanical engineer at Facebook, posted some stats about the Forest City data center in a blog over at the Open Compute Project, where those open source server and data center designs live.

Among other things, the charts show that the weather has been kind so far to the data center. When the heat has been on, the humidity has been low enough that evaporative cooling of the outside air has been sufficient to keep Zuck's servers from melting and Wall Street from gnashing its teeth even more than it already has about Facebook's finances.

As Lee puts it, Facebook knew that it was taking some risks with trying to cool the data center with outside air in a region that, as far as the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE) guidelines were concerned, was out of bounds because of the humidity levels.

Facebook's first data center, in Prineville, Oregon, used outside air cooling as well, but Prineville is an arid environment with cool nights and winters and hot, dry summers. As long as the air is dry, you can cool it with water.

But back in the swampy air of the US East Coast, you can get both heat and humidity, and then all the air conditioning in the world doesn't seem to help. And if you are trying to do outside-air cooling for the 100,000 servers in the Forest City data center, when the humidity and the heat are both on the rise you have a problem.

Lee says that Facebook hedged its bets and installed a direct expansion (DX) coil system – basically, an air conditioner like we have in our homes – in the Forest City data center, just in case it got too hot or too humid. Or both at the same time.

Because the weather is quite a bit different in Oregon and North Carolina, Lee says that the data center was tweaked to have a server inlet relative humidity of 90 per cent, considerably higher than the 65 per cent in Prineville, and a server inlet temperature of 85 degrees instead of 80 degrees out in Prineville.

And it worked.

The DX conditioners have not been turned on all year, despite the dry bulb temperatures outside of the Forest City data center being 100 degrees or higher several times in June and July.

The heat and humidity cut Facebook some slack in North Carolina this summer

The heat and humidity cut Facebook some slack in North Carolina this summer (click to enlarge)

In fact, says Lee, on July 1, when the outside temperature was 102 degrees (as measured by a dry bulb thermometer) during the afternoon, the relative humidity was only 26 per cent. In some cases, when the air was particularly moist, Facebook got lucky that temperatures were not that high and actually mixed in hot, relatively dry air coming off the servers back into the server inlet to lower the overall humidity of the inlet air, which was cool enough to pass back over the servers again.

The upshot is that you don't have to put your data centers in arid or cool areas to make it work – so long as you are happy to step outside the boundaries of the ASHRAE guidelines, as Facebook did:

If you can read this ASHRAE chart and ignore it, Facebook wants to hire you

If you can read this ASHRAE chart and ignore it, Facebook wants to hire you (click to enlarge)

Another interesting thing is that the Forest City data center was projected to have a power usage effectiveness (PUE) rating of between 1.06 and 1.08. PUE is the ratio of all of the power coming into the data center divided by the power consumption of the server, storage, and networking gear. A lot of old data centers have a PUE of around 2 or worse, while the best ones from Google, Facebook, and Yahoo! are around 1.10, and sometimes a little lower.

Despite the harsher weather conditions, Lee says the Forest City data center has attained a PUE of 1.07, smack dab in the projected range, for the summer. And it even bested the Prineville data center, which had a PUE of 1.09 over the same time. ®

High performance access to file storage

More from The Register

next story
Seagate brings out 6TB HDD, did not need NO STEENKIN' SHINGLES
Or helium filling either, according to reports
European Court of Justice rips up Data Retention Directive
Rules 'interfering' measure to be 'invalid'
Dropbox defends fantastically badly timed Condoleezza Rice appointment
'Nothing is going to change with Dr. Rice's appointment,' file sharer promises
Cisco reps flog Whiptail's Invicta arrays against EMC and Pure
Storage reseller report reveals who's selling what
Just what could be inside Dropbox's new 'Home For Life'?
Biz apps, messaging, photos, email, more storage – sorry, did you think there would be cake?
IT bods: How long does it take YOU to train up on new tech?
I'll leave my arrays to do the hard work, if you don't mind
Amazon reveals its Google-killing 'R3' server instances
A mega-memory instance that never forgets
USA opposes 'Schengen cloud' Eurocentric routing plan
All routes should transit America, apparently
prev story

Whitepapers

Mainstay ROI - Does application security pay?
In this whitepaper learn how you and your enterprise might benefit from better software security.
Five 3D headsets to be won!
We were so impressed by the Durovis Dive headset we’ve asked the company to give some away to Reg readers.
3 Big data security analytics techniques
Applying these Big Data security analytics techniques can help you make your business safer by detecting attacks early, before significant damage is done.
The benefits of software based PBX
Why you should break free from your proprietary PBX and how to leverage your existing server hardware.
Mobile application security study
Download this report to see the alarming realities regarding the sheer number of applications vulnerable to attack, as well as the most common and easily addressable vulnerability errors.