The Netflix's video streaming service has nearly tripled in growth during the past year. To scale the service, Netflix has moved its API and other operations to Amazon Web Services (AWS) over the past several months.

In an interview today on the Cloudscaling blog, Netflix Cloud Architect Adrian Cockcroft discusses why Netflix moved to AWS. He gives advice for those that wish to follow in Netflix's path. In particular, he outlines why a public cloud infrastructure has certain advantages compared to building out a data center.

Cloudscaling CEO Randy Bias conducted the interview. Cloudscaling works with telecommunications companies, service providers, and enterprises to build Infrastructure-as-a-Service (IaaS) environments. The interview is part of a series Bias is doing with cloud computing innovators.

Cockcroft said encoding movies for streaming, log analysis, the production website and the API moved from the Netflix data center to AWS, and that most everything that scales with customers and streaming usage is now on AWS.

Operations staying in Netflix data centers include "most internal IT that scales with employee count, legacy stuff, DVD shipping systems. account sign-up and billing systems," Cockcroft said.

Netflx uses Akamai, Limelight and Level3 content delivery networks for streaming movies. Cockcroft says that AWS CDN service isn't a big enough player in the space at this point to use for that service.

Cockcroft says business agility and the inability to predict capacity are the main drivers for moving to AWS. Business is accelerating. Netflix customer growth is up 52% compared to last year. Customers using streaming services are up 145% to 11 million subscribers.

The Return on Investment

Cockcroft says its Netflix data centers run Oracle on IBM hardware. He says Netflix could have added commodity hardware and scaled its data center but the cost would have been substantial.

It would have also meant hiring any number of systems administrators and database managers. In contrast, Cockcroft says Netflix has "added four to five times as many systems in the cloud as the total we have in our datacenter over the last year."

Scaling is elastic with AWS. Costs are based on usage. When Amazon drops prices, capacity gets cheaper for Netflix. When AWS introduces a new instance type, the technology is available within hours. AWS introduced its 11th new instance last week. It is called the Cluster GPU Instance processes and renders some of the most complex actions such as those required in financial services and the sciences.

Netflix Gives Some Advice

Cockcroft says the biggest challenge is to get in a Google mindset. It means re-architecting applications for a multi-tenant environment:

"You have to assume that the hardware and underlying services are ephemeral, unreliable and may be broken or unavailable at any point, and that the other tenants in the multi-tenant public cloud will add random congestion and variance. In reality you always had this problem at scale, even with the most reliable hardware, so cloud ready architecture is about taking the patterns you have to use at large scale, and using them at a smaller scale to leverage the lowest cost infrastructure."

The next challenge is a political one. Cockcroft says a CIO would prefer to build data centers than become irrelevant to internal customers. These internal customers will eventually turn to services like AWS. The cost comparisons are pretty clear. AWS is far less expensive.

"For me, if its not multi-tenant, it's not cloud, and only the biggest organizations should be building datacenters to host clouds, and they should be offering them publicly. If you are doing internal cloud and you have a dominant internal customer then you are doing it wrong, because you have to choose between baking in a lot of unused extra capacity or the risk that at some point that customer will blow up your cloud."

Compliance issues still create problems. Organizations do not consider the cloud in their checklists. That will change. It's just a matter of when it will occur.

In the end, Bias presents a solid testimony from Cockcroft about the disruptions we see in the market. The interview shows how one customer is scaling its services with a cloud infrastructure. That's helpful on a number of levels for companies considering a move to cloud computing.