Facebook's "Open Compute" Server testedby Johan De Gelas on November 3, 2011 12:00 AM EST
Facebook Technology Overview
Facebook had 22 Million active users in the middle of 2007; fast forward to 2011 and the site now has 800 Million active users, with 400 million of them logging in every day. Facebook has grown exponentially, to say the least! To cope with this kind of exceptional growth and at the same time offer a reliable and cost effective service requires out of the box thinking. Typical high-end, brute force, ultra redundant software and hardware platforms (for example Oracle RAC databases running on top of a few IBM Power 795 systems) won’t do as they're too complicated, power hungry, and most importantly far too expensive for such extreme scaling.
Facebook first focused on thoroughly optimizing their software architecture, which we will cover briefly. The next step was the engineers at Facebook deciding to build their own servers to minimize the power and cost of their server infrastructure. Facebook Engineering then open sourced these designs to the community; you can download the specifications and mechanical CAD designs at the Open Compute site.
The Facebook Open Compute server design is ambitious: “The result is a data center full of vanity free servers which is 38% more efficient and 24% less expensive to build and run than other state-of-the-art data centers.” Even better is that Facebook Engineering sent two of these Open Compute servers to our lab for testing, allowing us to see how these servers compare to other solutions in the market.
As a competing solution we have an HP DL380 G7 in the lab. Recall from our last server clash that the HP DL380 G7 was one of the most power efficient servers of 2010. Is a server "targeted at the cloud" and designed by Facebook engineering able to beat one of the best and most popular general purpose servers? That is the question we'll answer in this article.
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harrkev - Thursday, November 3, 2011 - linkYou should look again at the sine-wave plots. Power factor has more to do with the phase of the current and not so much how much like a sine-wave it looks like.
As an example, a purely capacitive or purely inductive load will have a perfect sine wave current (but completely out of phase with the voltage), but have a power factor very close to zero...
So, those graphs do not really tell us much unless you actually crank the numbers to calculate the real power factor.
ezekiel68 - Thursday, November 3, 2011 - linkOn page 2:
"The next piece in the Facebook puzzle is that the Open Source tools are Memcached."
In fact, the tools are not memchached. Instead, software objects from the PHP/c++ stack, programmed by the engineers, are stored in Memcached. Side note - those in the know pronounce it "mem-cache-dee", emphasizing with the last syllable that it is a network daemon. (similar to how the DNS server "bind" is pronounced "bin-dee") So the next piece is Memcached, but the tools are not 'memcached'.
JohanAnandtech - Thursday, November 3, 2011 - linkThat is something that went wrong in the final editing by Jarred. Sorry about that and I feel bad about dragging Jarred into this, but unfortunately that is what happened. As you can see further, "Facebook mostly uses memcached to alleviate database load", I was not under the impression that the "Open Source tools are Memcached. " :-)
ezekiel68 - Thursday, November 3, 2011 - linkI was pretty sure it was a mistake and I only mentioned it to have the blemish removed - I've been following and admiring your technical writing since the the early 2000s. Please keep on bringing us great server architecture pieces. Don't worry about Jarred, he's fine too. We all make mistakes.
Dug - Thursday, November 3, 2011 - linkI'm curious what the cost would be on the servers compared to something like the HP.
Lucian Armasu - Thursday, November 3, 2011 - linkAccording to SemiAccurate, Facebook is considering Calxeda's recently announced ARM servers, too. It could be a lot more efficient to run something like Facebook on those types of servers.
JohanAnandtech - Thursday, November 3, 2011 - linkI personally doubt that very much. The memcached servers are hardly CPU intensive, but a 32 bit ARM processor will not fit the bill. Even when ARM will get 64 bit, it is safe to say that x86 will offer much more DIMM slots. It remains to be seen how the ratio Watt/ RAM cache will be. Until 64 bit ARMs arrive with quite a few memory channels: no go IMHO.
And the processing intensive parts of the facebook architecture are going to be very slow on the ARMs.
The funny thing about the ARM presentations is that they assume that virtualization does not exist in the x86 world. A 24 thread x86 CPU with 128 GB can maybe run 30-60 VMs on it, lowering the cost to something like 5-10W per VM. A 5W ARM server is probably not even capable of running one of those machines at a decent speed. You'll be faced with serious management overhead to deal with 30x more servers (or worse!), high response times (single thread performance take a huge dive!) just to save a bit on the power bill.
As a general rule: if the Atom based servers have not made it to the shortlist yet, they sure are not going to replace it by ARM based ones.
tspacie - Thursday, November 3, 2011 - linkThe FaceBook servers take a higher line voltage for increased efficiency. What voltage was supplied to the HP server for these tests?
JohanAnandtech - Thursday, November 3, 2011 - linkBoth servers used 230V. I have added this to benchmark page (Thanks, good question). So in reality the Facebook server can consume slightly less.
Alex_Haddock - Thursday, November 3, 2011 - linkTBH we'd position SL class servers for this kind of scenario rather than DL380G7 (which does have a DC power option btw) so not sure it is a relevant comparison. Though I understand using what is available to test.