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Social Machinery

  • by Stephen Cass
  • June 21, 2011
  • 1. FACEBOOK PAGE: Each Web page is assembled from data drawn from different systems within the data center. These include systems responsible for photographs (blue), the news feed (green), the “Like” button (purple), third-party applications such as games (pink), and advertisements (yellow).
    2. CONTENT DELIVERY NETWORK: Commercial services store and distribute pages to users so that data centers don’t become bottlenecked.
    3. OTHER DATA CENTERS: Several data centers share information directly with one another, allowing for load balancing and rapid synchronization of user data.
    4. PHOTOGRAPHS: The more than 100 million photos uploaded daily are stored in a distributed database called Haystack, developed by Facebook.
    5. ELECTRICAL SUBSTATION: The electrical system distributes 277 volts to servers rather than the 208 or 120 volts typical for data centers. Conversion losses from the utility connection to the server are only 2 percent, rather than the typical 11 to 17 percent.
    6. SECURITY: Connections from third-party sites are analyzed to guard against malware.
    7. THIRD-PARTY PROVIDERS: Data feeds come from external sources, such as Zynga, which operates the popular FarmVille game.
    8. FACEBOOK PLATFORM: Servers provide an interface for external developers to use in creating apps that can be integrated into Facebook pages or websites that work with the social network.
    9. “LIKE” BUTTON: These servers track how users on Facebook—and a growing number of external sites—are using the “Like” button to signify interest in Web pages.
    10. NEWS FEED: This is where posts from other users and notifications from applications are filtered and assembled into a chronological list.
    11. WEB SERVERS AND CACHES: Data from the other servers in the center is assembled and formatted into the HTML that makes up a Web page in servers (orange) running PHP, an open-source scripting language. Frequently accessed content is cached in intermingled servers (blue) for rapid retrieval without overloading the internal infrastructure of the data center.
    12. RACK SERVER: Prineville’s servers use a new design with a high-efficiency power supply. It can accept either 277 volts of AC power or backup DC power from battery cabinets that can each supply multiple servers.

A single page on a social-networking website is an amalgam of many different technologies. Each user is served a unique page assembled from up-to-the-second information from multiple sources. During assembly, attention must be paid to each user’s personal preferences, the privacy settings of the user’s friends (and friends of friends), and the advertisements that seem most likely to find a favorable reception (see “Managing Users by the Million”). Here we show some of the hardware and software required to support key elements of a typical page belonging to one of Facebook’s 600 million active users.

The hardware depicted is largely located in the company’s new 31,000-square-meter data center in Prineville, Oregon. This facility uses evaporative cooling to control temperatures. Facebook claims that the cooling technology, together with a new electricity distribution system, has made the data center 38 percent more energy efficient than a traditional center, with operating costs about 24 percent lower.

Facebook has made the designs for the Prineville data center, and the customized servers within it, available to anyone—a decision that reflects in the physical sphere the social network’s heavy use of open-source projects in its software.

This story is part of our July/August 2011 Issue
See the rest of the issue

Image Credit: Bryan Christie Design

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