Pandora Scales to Serve Tens of Millions of Internet Radio Users with F5 Solution

Internet radio provider Pandora needed an Application Delivery Controller (ADC) solution to help it scale to serve tens of millions of users with no downtime or performance issues. By upgrading to F5 BIG-IP systems, and eventually to F5 VIPRION devices, Pandora was able to scale to tens of millions of users with plenty of room for more customer growth, while maintaining the best performance and reliability in the business. Thanks to the ease of installation and configuration of the VIRPRION devices, Pandora’s engineers can focus on improving Internet radio services rather than troubleshooting ADC systems.

Business Challenges

Launched in 2005, Pandora is the leading Internet radio service, streaming personalized music and comedy to tens of millions of listeners worldwide based on each user’s individual preferences.

Pandora’s continuing challenge is scale.  With listeners tuning in for more than a billion hours per month, Pandora must always be ready to handle massive amounts of traffic with top-level performance. “Since we’re an Internet radio service, we want users to have the best possible listening experience with no delays or outages,” says James Kelty, Director of Network Engineering for Pandora. “We have to be sure we can always handle the next wave of users and user traffic six months down the road.”

Five years ago, Pandora was using a different Application Delivery Controller (ADC) to distribute user application requests to a data center farm of music delivery servers. However, the solution wasn’t meeting Pandora’s scalability and performance needs. “Our ADC solution was just not living up to the vendor’s promises,” says Kelty. “We needed 14 ADC units in one data center—including 2 for failover—just for audio delivery.” Pandora’s ADC solution also required its already overextended engineering team to create and implement manual tweaks and workarounds just to allow application server nodes to be taken down for servicing and updates.

When the two failover ADC units proved incapable of handling Pandora’s traffic volume, leading to significant downtime, Pandora decided it was time for a change.  “We needed a solution that would do what the vendor promised, with a solid code base that wouldn’t force us to devise all kinds of tweaks, scripts, and workarounds,” says Kelty. “We needed a solution capable of handling 100 application server nodes or more in a single pool without any performance bottlenecks.”

Finally, Pandora was looking for a product that could manage SSL offload at a future date. The result was a transition to F5 BIG-IP systems in 2007, which lasted Pandora through five years of enormous growth.

In 2012, Pandora decided its projected growth required another ADC upgrade, with even more massive scalability than it had needed in the past.


In 2007, Pandora considered several replacement ADC solutions and ran pilot testing on three. F5 BIG-IP systems won hands down, according to Kelty. “F5’s implementation was very quick, thanks to a knowledgeable engineering group that could answer all our questions on the spot, and the solution outperformed all the others we tested,” he says.

Pandora started with two pairs of BIG-IP 6400 devices, which it upgraded to BIG-IP 8900 devices a few years later. “Our growth accelerated so fast that, last year, we felt it was time to upgrade to a solution that would allow us to add a lot more capacity without having to upgrade the entire device.” This led Pandora to F5 VIPRION.

Instead of forcing organizations to replace the entire ADC unit or purchase additional units when traffic volume surpasses its capabilities, the VIPRION solution provides application delivery in a blade server chassis configuration. The F5 ScaleN architecture of VIPRION allows organizations to start with a single ADC blade and scale as required by adding blades. “We were able to start with a single pair of VIPRION chassis, with a single blade in each, and will be able to add up to three more blades as traffic needs dictate.”

Pandora also decided to deploy two pairs of F5 BIG-IP Global Traffic Manager (GTM) devices in its West Coast and East Coast data centers to ensure users would experience superior streaming audio performance.


From both its original F5 BIG-IP systems and the recent F5 VIPRION upgrade, Pandora realized several benefits, including superior scalability, performance, and uptime, as well as enhanced user satisfaction.

Superior scalability with smooth, consistent performance

With its original BIG-IP systems, Pandora was able to create load balancing pools of up to 100 or more application server nodes. These delivered smooth application performance and presented no performance hotspots or bottlenecks. As a result, Pandora could serve its more than 62 million and growing numbers of users with consistent, top-notch performance.

The F5 VIPRION solution enables Pandora to continue to scale smoothly for years without having to replace its current load balancing devices. “With VIPRION, we can deploy the same ADCs and architecture for years to come, despite tremendous projected growth,” says Kelty. “We can plan much more easily now because we can scale within the VIPRION chassis itself. And unlike with the previous vendor’s ADC solutions, we are confident the F5 systems will perform as advertised.”

Superior uptime

Thanks to F5’s easily configurable server health check capabilities, Pandora can now remove application server nodes from the server pool for maintenance or software upgrades without any service hiccups. Both the BIG-IP and VIPRION systems simply detect the dropped servers and allocate incoming requests to the remaining servers in the pool automatically.

Easy installation, configuration, and management 

Pandora found installation and configuration of the F5 BIG IP systems quick and easy. When it was time to upgrade to F5 VIPRION, little reconfiguration was required. “The VIPRION system was able to read the configuration information from the existing F5 BIG-IP devices and implement much of the same configuration automatically,” says Kelty. Thanks to F5 iControl configuration and management APIs, Pandora was able to integrate the BIG-IP and VIPRION systems into its existing network management infrastructure with very little effort.

When it was time to activate SSL offload on the F5 systems, configuration was also very simple, according to Kelty. “Our engineering group was impressed with how quickly they could get it in place and working,” he says. Since there’s no longer any need for manual scripts and workarounds, Pandora’s engineering team can focus on improving Pandora’s Internet radio application rather than wrestling with ADC quirks and challenges.

Enhanced customer satisfaction Thanks to the excellent performance and uptime the F5 solution provides, Pandora has been able to deliver performance and customer satisfaction superior to that of its competition. Apica, a creator of web performance monitoring tools, recently compared popular web music services and placed Pandora at the top with 99.98% availability and 3.4 seconds average response time.

“The best thing about the F5 solution is that it can scale your infrastructure smoothly without being an onerous device,” says Kelty. “You just plug it in and it works. Thanks to F5, we were able to stabilize our existing environment and scale easily to meet future needs.”

Steve Ginsberg, VP of Technical Operations at Pandora, sums up the company’s experience with F5. He says, “It’s been a great decision to partner with F5. Our installation has been highly stable as a result of F5’s excellent technical consultation and solid product.”

Pandora logo
  • Scale to tens of millions of users without decline in performance
  • Serve all application nodes with one load balancing solution
  • Perform application server maintenance without specialized scripts

  • Scales to serve tens of millions of users
  • Delivers superior uptime
  • Eases server maintenance
  • Improves performance, resulting in Pandora top ranking in speed and reliability