How do you move an entire data center to the public cloud? And if you’re a SaaS provider like Evernote, how do you do all that safely, securely, and without your millions of active users even noticing?

Here is a fascinating account of the why and how Evernote, the popular cross-platform note-taking app, moved their infrastructure from two private data centers to Google’s public cloud platform, transferring 3 petabytes of data in the process. The entire operation involved moving some 5 billion notes and 12 billion files, and took some 70 days, and a whole lot of engineering work. That’s a whole lot of notes and clippings!

Why this decision to go the public cloud route, and why Google Cloud in particular?

Machine learning was a highlight of Google’s platform for Evernote CTO Anirban Kundu, who said that higher-level services offered by Google help provide the foundation for new and improved features. Evernote has been driving toward a set of new capabilities based on machine learning, and Google services like its Cloud Machine Learning API help with that.

While cost is often touted as a benefit of cloud migrations, McCormack said that it wasn’t a primary driver of Evernote’s migration. While the company will be getting some savings out of the move, he said that cost wasn’t a limitation for the transition.

`The decision to go with Google over another provider like AWS or Azure was driven by the technology team at Evernote, according to Greg Chiemingo, the company’s senior director of communications. He said in an email that CEO Chris O’Neill, who was at Google for roughly a decade before joining Evernote, came in to help with negotiations after the decision was made.

This is something I’ve heard over and over again, and even seen myself with the insignificantly tiny infrastructure that I manage. In the grand scheme of things, cloud computing is hardly about cost savings. Companies move their infrastructure to the cloud for such other benefits as scalability, elasticity (the ability to scale your infrastructure up and down based on load — which is often the primary reason for cost savings), and, in Evernote’s case, availability of and proximity to “upstream” services and APIs.

The PCWorld article has details of the actual migration, including the critical role that Google’s engineers played to make this a success. Of course, Google had EVERY reason to ensure the success of this migration: just imagine what the headlines would be if there was a catastrophic failure, whether Google had anything to do with the failure or not!