MySpace Scaling Story

A Member Rants

On his MySpace profile page, Drew, a 17-year-old from Dallas, is bare-chested, in a photo that looks like he might have taken it of himself, with the camera held at arm's length. His "friends list" is weighted toward pretty girls and fast cars, and you can read that he runs on the school track team, plays guitar and drives a blue Ford Mustang.

But when he turns up in the forum where users vent their frustrations, he's annoyed. "FIX THE GOD DAMN INBOX!" he writes, "shouting" in all caps. Drew is upset because the private messaging system for MySpace members will let him send notes and see new ones coming in, but when he tries to open a message, the Web site displays what he calls "the typical sorry ... blah blah blah [error] message."

For MySpace, the good news is that Drew cares so much about access to this online meeting place, as do the owners of 140 million other MySpace accounts. That's what has made MySpace one of the world's most trafficked Web sites.

In November, MySpace, for the first time, surpassed even Yahoo in the number of Web pages visited by U.S. Internet users, according to comScore Media Metrix, which recorded 38.7 billion page views for MySpace as opposed to 38.05 billion for Yahoo.

The bad news is that MySpace reached this point so fast, just three years after its official launch in November 2003, that it has been forced to address problems of extreme scalability that only a few other organizations have had to tackle.

The result has been periodic overloads on MySpace's Web servers and database, with MySpace users frequently seeing a Web page headlined "Unexpected Error" and other pages that apologize for various functions of the Web site being offline for maintenance. And that's why Drew and other MySpace members who can't send or view messages, update their profiles or perform other routine tasks pepper MySpace forums with complaints.

These days, MySpace seems to be perpetually overloaded, according to Shawn White, director of outside operations for the Keynote Systems performance monitoring service. "It's not uncommon, on any particular day, to see 20% errors logging into the MySpace site, and we've seen it as high as 30% or even 40% from some locations," he says. "Compare that to what you would expect from Yahoo or Salesforce.com, or other sites that are used for commercial purposes, and it would be unacceptable." On an average day, he sees something more like a 1% error rate from other major Web sites.

In addition, MySpace suffered a 12-hour outage, starting the night of July 24, 2006, during which the only live Web page was an apology about problems at the main data center in Los Angeles, accompanied by a Flash-based Pac-Man game for users to play while they waited for service to be restored. (Interestingly, during the outage, traffic to the MySpace Web site went up, not down, says Bill Tancer, general manager of research for Web site tracking service Hitwise: "That's a measure of how addicted people are—that all these people were banging on the domain, trying to get in.")

Jakob Nielsen, the former Sun Microsystems engineer who has become famous for his Web site critiques as a principal of the Nielsen Norman Group consultancy, says it's clear that MySpace wasn't created with the kind of systematic approach to computer engineering that went into Yahoo, eBay or Google. Like many other observers, he believes MySpace was surprised by its own growth. "I don't think that they have to reinvent all of computer science to do what they're doing, but it is a large-scale computer science problem," he says.

MySpace developers have repeatedly redesigned the Web site's software, database and storage systems to try to keep pace with exploding growth, but the job is never done. "It's kind of like painting the Golden Gate Bridge, where every time you finish, it's time to start over again," says Jim Benedetto, MySpace's vice president of technology.

So, why study MySpace's technology? Because it has, in fact, overcome multiple systems scalability challenges just to get to this point.

Benedetto says there were many lessons his team had to learn, and is still learning, the hard way. Improvements they are currently working on include a more flexible data caching system and a geographically distributed architecture that will protect against the kind of outage MySpace experienced in July.

Most corporate Web sites will never have to bear more than a small fraction of the traffic MySpace handles, but anyone seeking to reach the mass market online can learn from its example.

The Journey Begins

MySpace may be struggling with scalability issues today, but its leaders started out with a keen appreciation for the importance of Web site performance.

The Web site was launched a little more than three years ago by an Internet marketing company called Intermix Media (also known, in an earlier incarnation, as eUniverse), which ran an assortment of e-mail marketing and Web businesses. MySpace founders Chris DeWolfe and Tom Anderson had previously founded an e-mail marketing company called ResponseBase that they sold to Intermix in 2002. The ResponseBase team received $2 million plus a profit-sharing deal, according to a Web site operated by former Intermix CEO Brad Greenspan. (Intermix was an aggressive Internet marketer—maybe too aggressive. In 2005, then New York Attorney General Eliot Spitzer—now the state's governor—won a $7.9 million settlement in a lawsuit charging Intermix with using adware. The company admitted no wrongdoing.)

In 2003, Congress passed the CAN-SPAM Act to control the use of unsolicited e-mail marketing. Intermix's leaders, including DeWolfe and Anderson, saw that the new laws would make the e-mail marketing business more difficult and "were looking to get into a new line of business," says Duc Chau, a software developer who was hired by Intermix to rewrite the firm's e-mail marketing software.

At the time, Anderson and DeWolfe were also members of Friendster, an earlier entrant in the category MySpace now dominates, and they decided to create their own social networking site. Their version omitted many of the restrictions Friendster placed on how users could express themselves, and they also put a bigger emphasis on music and allowing bands to promote themselves online. Chau developed the initial version of the MySpace Web site in Perl, running on the Apache Web server, with a MySQL database back end. That didn't make it past the test phase, however, because other Intermix developers had more experience with ColdFusion, the Web application environment originally developed by Allaire and now owned by Adobe. So, the production Web site went live on ColdFusion, running on Windows, and Microsoft SQL Server as the database.

Chau left the company about then, leaving further Web development to others, including Aber Whitcomb, an Intermix technologist who is now MySpace's chief technology officer, and Benedetto, who joined about a month after MySpace went live.

MySpace was launched in 2003, just as Friendster started having trouble keeping pace with its own runaway growth. In a recent interview with Fortune magazine, Friendster president Kent Lindstrom admitted his service stumbled at just the wrong time, taking 20 to 30 seconds to deliver a page when MySpace was doing it in 2 or 3 seconds.

As a result, Friendster users began to defect to MySpace, which they saw as more dependable.

Today, MySpace is the clear "social networking" king. Social networking refers to Web sites organized to help users stay connected with each other and meet new people, either through introductions or searches based on common interests or school affiliations. Other prominent sites in this category include Facebook, which originally targeted university students; and LinkedIn, a professional networking site, as well as Friendster. MySpace prefers to call itself a "next generation portal," emphasizing a breadth of content that includes music, comedy and videos. It operates like a virtual nightclub, with a juice bar for under-age visitors off to the side, a meat-market dating scene front and center, and marketers in search of the youth sector increasingly crashing the party.

Users register by providing basic information about themselves, typically including age and hometown, their sexual preference and their marital status. Some of these options are disabled for minors, although MySpace continues to struggle with a reputation as a stomping ground for sexual predators.

MySpace profile pages offer many avenues for self-expression, ranging from the text in the About Me section of the page to the song choices loaded into the MySpace music player, video choices, and the ranking assigned to favorite friends. MySpace also gained fame for allowing users a great deal of freedom to customize their pages with Cascading Style Sheets (CSS), a Web standard formatting language that makes it possible to change the fonts, colors and background images associated with any element of the page. The results can be hideous—pages so wild and discolored that they are impossible to read or navigate—or they can be stunning, sometimes employing professionally designed templates (see "Too Much of a Good Thing?" p. 48).

The "network effect," in which the mass of users inviting other users to join MySpace led to exponential growth, began about eight months after the launch "and never really stopped," Chau says.

News Corp., the media empire that includes the Fox television networks and 20th Century Fox movie studio, saw this rapid growth as a way to multiply its share of the audience of Internet users, and bought MySpace in 2005 for $580 million. Now, News Corp. chairman Rupert Murdoch apparently thinks MySpace should be valued like a major Web portal, recently telling a group of investors he could get $6 billion—more than 10 times the price he paid in 2005—if he turned around and sold it today. That's a bold claim, considering the Web site's total revenue was an estimated $200 million in the fiscal year ended June 2006. News Corp. says it expects Fox Interactive as a whole to have revenue of $500 million in 2007, with about $400 million coming from MySpace.

But MySpace continues to grow. In December, it had 140 million member accounts, compared with 40 million in November 2005. Granted, that doesn't quite equate to the number of individual users, since one person can have multiple accounts, and a profile can also represent a band, a fictional character like Borat, or a brand icon like the Burger King.

Still, MySpace has tens of millions of people posting messages and comments or tweaking their profiles on a regular basis—some of them visiting repeatedly throughout the day. That makes the technical requirements for supporting MySpace much different than, say, for a news Web site, where most content is created by a relatively small team of editors and passively consumed by Web site visitors. In that case, the content management database can be optimized for read-only requests, since additions and updates to the database content are relatively rare. A news site might allow reader comments, but on MySpace user-contributed content is the primary content. As a result, it has a higher percentage of database interactions that are recording or updating information rather than just retrieving it.

Every profile page view on MySpace has to be created dynamically—that is, stitched together from database lookups. In fact, because each profile page includes links to those of the user's friends, the Web site software has to pull together information from multiple tables in multiple databases on multiple servers. The database workload can be mitigated somewhat by caching data in memory, but this scheme has to account for constant changes to the underlying data.

The Web site architecture went through five major revisions—each coming after MySpace had reached certain user account milestones—and dozens of smaller tweaks, Benedetto says. "We didn't just come up with it; we redesigned, and redesigned, and redesigned until we got where we are today," he points out.

Although MySpace declined formal interview requests, Benedetto answered Baseline's questions during an appearance in November at the SQL Server Connections conference in Las Vegas. Some of the technical information in this story also came from a similar "mega-sites" presentation that Benedetto and his boss, chief technology officer Whitcomb, gave at Microsoft's MIX Web developer conference in March.

As they tell it, many of the big Web architecture changes at MySpace occurred in 2004 and early 2005, as the number of member accounts skyrocketed into the hundreds of thousands and then millions.

At each milestone, the Web site would exceed the maximum capacity of some component of the underlying system, often at the database or storage level. Then, features would break, and users would scream. Each time, the technology team would have to revise its strategy for supporting the Web site's workload.

And although the systems architecture has been relatively stable since the Web site crossed the 7 million account mark in early 2005, MySpace continues to knock up against limits such as the number of simultaneous connections supported by SQL Server, Benedetto says: "We've maxed out pretty much everything."

First Milestone: 500,000 Accounts

MySpace started small, with two Web servers talking to a single database server. Originally, they were 2-processor Dell servers loaded with 4 gigabytes of memory, according to Benedetto.

Web sites are better off with such a simple architecture—if they can get away with it, Benedetto says. "If you can do this, I highly recommend it because it's very, very non-complex," he says. "It works great for small to medium-size Web sites."

The single database meant that everything was in one place, and the dual Web servers shared the workload of responding to user requests. But like several subsequent revisions to MySpace's underlying systems, that three-server arrangement eventually buckled under the weight of new users. For a while, MySpace absorbed user growth by throwing hardware at the problem—simply buying more Web servers to handle the expanding volume of user requests.

But at 500,000 accounts, which MySpace reached in early 2004, the workload became too much for a single database.

Adding databases isn't as simple as adding Web servers. When a single Web site is supported by multiple databases, its designers must decide how to subdivide the database workload while maintaining the same consistency as if all the data were stored in one place.

In the second-generation architecture, MySpace ran on three SQL Server databases—one designated as the master copy to which all new data would be posted and then replicated to the other two, which would concentrate on retrieving data to be displayed on blog and profile pages. This also worked well—for a while—with the addition of more database servers and bigger hard disks to keep up with the continued growth in member accounts and the volume of data being posted.

Second Milestone: 1-2 Million Accounts

As MySpace registration passed 1 million accounts and was closing in on 2 million, the service began knocking up against the input/output (I/O) capacity of the database servers—the speed at which they were capable of reading and writing data. This was still just a few months into the life of the service, in mid-2004. As MySpace user postings backed up, like a thousand groupies trying to squeeze into a nightclub with room for only a few hundred, the Web site began suffering from "major inconsistencies," Benedetto says, meaning that parts of the Web site were forever slightly out of date.

"A comment that someone had posted wouldn't show up for 5 minutes, so users were always complaining that the site was broken," he adds.

The next database architecture was built around the concept of vertical partitioning, with separate databases for parts of the Web site that served different functions such as the log-in screen, user profiles and blogs. Again, the Web site's scalability problems seemed to have been solved—for a while.

The vertical partitioning scheme helped divide up the workload for database reads and writes alike, and when users demanded a new feature, MySpace would put a new database online to support it. At 2 million accounts, MySpace also switched from using storage devices directly attached to its database servers to a storage area network (SAN), in which a pool of disk storage devices are tied together by a high-speed, specialized network, and the databases connect to the SAN. The change to a SAN boosted performance, uptime and reliability, Benedetto says.

Third Milestone: 3 Million Accounts

As the Web site's growth continued, hitting 3 million registered users, the vertical partitioning solution couldn't last. Even though the individual applications on sub-sections of the Web site were for the most part independent, there was also information they all had to share. In this architecture, every database had to have its own copy of the users table—the electronic roster of authorized MySpace users. That meant when a new user registered, a record for that account had to be created on nine different database servers. Occasionally, one of those transactions would fail, perhaps because one particular database server was momentarily unavailable, leaving the user with a partially created account where everything but, for example, the blog feature would work for that person.

And there was another problem. Eventually, individual applications like blogs on sub-sections of the Web site would grow too large for a single database server.

By mid-2004, MySpace had arrived at the point where it had to make what Web developers call the "scale up" versus "scale out" decision—whether to scale up to bigger, more powerful and more expensive servers, or spread out the database workload across lots of relatively cheap servers. In general, large Web sites tend to adopt a scale-out approach that allows them to keep adding capacity by adding more servers.

But a successful scale-out architecture requires solving complicated distributed computing problems, and large Web site operators such as Google, Yahoo and Amazon.com have had to invent a lot of their own technology to make it work. For example, Google created its own distributed file system to handle distributed storage of the data it gathers and analyzes to index the Web.

In addition, a scale-out strategy would require an extensive rewrite of the Web site software to make programs designed to run on a single server run across many—which, if it failed, could easily cost the developers their jobs, Benedetto says.

So, MySpace gave serious consideration to a scale-up strategy, spending a month and a half studying the option of upgrading to 32-processor servers that would be able to manage much larger databases, according to Benedetto. "At the time, this looked like it could be the panacea for all our problems," he says, wiping away scalability issues for what appeared then to be the long term. Best of all, it would require little or no change to the Web site software.

Unfortunately, that high-end server hardware was just too expensive—many times the cost of buying the same processor power and memory spread across multiple servers, Benedetto says. Besides, the Web site's architects foresaw that even a super-sized database could ultimately be overloaded, he says: "In other words, if growth continued, we were going to have to scale out anyway."

So, MySpace moved to a distributed computing architecture in which many physically separate computer servers were made to function like one logical computer. At the database level, this meant reversing the decision to segment the Web site into multiple applications supported by separate databases, and instead treat the whole Web site as one application. Now there would only be one user table in that database schema because the data to support blogs, profiles and other core features would be stored together.

Now that all the core data was logically organized into one database, MySpace had to find another way to divide up the workload, which was still too much to be managed by a single database server running on commodity hardware. This time, instead of creating separate databases for Web site functions or applications, MySpace began splitting its user base into chunks of 1 million accounts and putting all the data keyed to those accounts in a separate instance of SQL Server. Today, MySpace actually runs two copies of SQL Server on each server computer, for a total of 2 million accounts per machine, but Benedetto notes that doing so leaves him the option of cutting the workload in half at any time with minimal disruption to the Web site architecture.

There is still a single database that contains the user name and password credentials for all users. As members log in, the Web site directs them to the database server containing the rest of the data for their account. But even though it must support a massive user table, the load on the log-in database is more manageable because it is dedicated to that function alone.

Fourth Milestone: 9 Million – 17 Million Accounts

When MySpace reached 9 million accounts, in early 2005, it began deploying new Web software written in Microsoft's C# programming language and running under ASP.NET. C# is the latest in a long line of derivatives of the C programming language, including C++ and Java, and was created to dovetail with the Microsoft .NET Framework, Microsoft's model architecture for software components and distributed computing. ASP.NET, which evolved from the earlier Active Server Pages technology for Web site scripting, is Microsoft's current Web site programming environment.

Almost immediately, MySpace saw that the ASP.NET programs ran much more efficiently, consuming a smaller share of the processor power on each server to perform the same tasks as a comparable ColdFusion program. According to CTO Whitcomb, 150 servers running the new code were able to do the same work that had previously required 246. Benedetto says another reason for the performance improvement may have been that in the process of changing software platforms and rewriting code in a new language, Web site programmers reexamined every function for ways it could be streamlined.

Eventually, MySpace began a wholesale migration to ASP.NET. The remaining ColdFusion code was adapted to run on ASP.NET rather than on a Cold-Fusion server, using BlueDragon.NET, a product from New Atlanta Communications of Alpharetta, Ga., that automatically recompiles ColdFusion code for the Microsoft environment.

When MySpace hit 10 million accounts, it began to see storage bottlenecks again. Implementing a SAN had solved some early performance problems, but now the Web site's demands were starting to periodically overwhelm the SAN's I/O capacity—the speed with which it could read and write data to and from disk storage.

Part of the problem was that the 1 million-accounts-per-database division of labor only smoothed out the workload when it was spread relatively evenly across all the databases on all the servers. That was usually the case, but not always. For example, the seventh 1 million-account database MySpace brought online wound up being filled in just seven days, largely because of the efforts of one Florida band that was particularly aggressive in urging fans to sign up.

Whenever a particular database was hit with a disproportionate load, for whatever reason, the cluster of disk storage devices in the SAN dedicated to that database would be overloaded. "We would have disks that could handle significantly more I/O, only they were attached to the wrong database," Benedetto says.

At first, MySpace addressed this issue by continually redistributing data across the SAN to reduce these imbalances, but it was a manual process "that became a full-time job for about two people," Benedetto says.

The longer-term solution was to move to a virtualized storage architecture where the entire SAN is treated as one big pool of storage capacity, without requiring that specific disks be dedicated to serving specific applications. MySpace now standardized on equipment from a relatively new SAN vendor, 3PARdata of Fremont, Calif., that offered a different approach to SAN architecture.

In a 3PAR system, storage can still be logically partitioned into volumes of a given capacity, but rather than being assigned to a specific disk or disk cluster, volumes can be spread or "striped" across thousands of disks. This makes it possible to spread out the workload of reading and writing data more evenly. So, when a database needs to write a chunk of data, it will be recorded to whichever disks are available to do the work at that moment rather than being locked to a disk array that might be overloaded. And since multiple copies are recorded to different disks, data can also be retrieved without overloading any one component of the SAN.

To further lighten the burden on its storage systems when it reached 17 million accounts, in the spring of 2005 MySpace added a caching tier—a layer of servers placed between the Web servers and the database servers whose sole job was to capture copies of frequently accessed data objects in memory and serve them to the Web application without the need for a database lookup. In other words, instead of querying the database 100 times when displaying a particular profile page to 100 Web site visitors, the site could query the database once and fulfill each subsequent request for that page from the cached data. Whenever a page changes, the cached data is erased from memory and a new database lookup must be performed—but until then, the database is spared that work, and the Web site performs better.

The cache is also a better place to store transitory data that doesn't need to be recorded in a database, such as temporary files created to track a particular user's session on the Web site—a lesson that Benedetto admits he had to learn the hard way. "I'm a database and storage guy, so my answer tended to be, let's put everything in the database," he says, but putting inappropriate items such as session tracking data in the database only bogged down the Web site.

The addition of the cache servers is "something we should have done from the beginning, but we were growing too fast and didn't have time to sit down and do it," Benedetto adds

Fifth Milestone: 26 Million Accounts

In mid-2005, when the service reached 26 million accounts, MySpace switched to SQL Server 2005 while the new edition of Microsoft's database software was still in beta testing. Why the hurry? The main reason was this was the first release of SQL Server to fully exploit the newer 64-bit processors, which among other things significantly expand the amount of memory that can be accessed at one time. "It wasn't the features, although the features are great," Benedetto says. "It was that we were so bottlenecked by memory."

More memory translates into faster performance and higher capacity, which MySpace sorely needed. But as long as it was running a 32-bit version of SQL Server, each server could only take advantage of about 4 gigabytes of memory at a time. In the plumbing of a computer system, the difference between 64 bits and 32 bits is like widening the diameter of the pipe that allows information to flow in and out of memory. The effect is an exponential increase in memory access. With the upgrade to SQL Server 2005 and the 64-bit version of Windows Server 2003, MySpace could exploit 32 gigabytes of memory per server, and in 2006 it doubled its standard configuration to 64 gigabytes.