Kundu said that Evernote had tested live migration prior to making the switch over to GCP, but that wasn’t enough.
When an application is put into production, user behavior and load on it might be different from test conditions, Kundu said. “And that’s where you have to be ready to handle those edge cases, and you have to realize that the day the migration happens or completes is not the day that you’re all done with the effort. You might see the problem in a month or whatever.”
Another key lesson, in McCormack’s opinion, is that the cloud is ready to handle any sort of workload. Evernote evaluated a migration roughly once every year, and it was only about 13 months ago that the company felt confident a cloud transition would be successful.
“Cloud has reached a maturity level and a breadth of features that means it’s unlikely that you’ll be unable to run in the cloud,” McCormack said.
That’s not to say it doesn’t require effort. While the cloud does provide benefits to Evernote that the company wasn’t going to get from running its own data center, they still had to cede control of their environment, and be willing to lose some of the telemetry they’re used to getting from a private data center.
Evernote’s engineers also did a lot of work on automating the transition. Moving users’ attachments over from the service’s on-premises infrastructure to Google Cloud Storage is handled by a pair of bespoke automated systems. The company used Puppet and Ansible for migrating the hundreds of shards holding user note data.
The immediate benefits of a migration
One of the key benefits of Evernote’s move to Google’s cloud is the company’s ability to provide reduced latency and improved connection consistency to its international customers. Evernote’s backend isn’t running in a geographically distributed manner right now, but Google’s worldwide networking investments provide an improvement right away.
“We have seen page loading times reducing quite significantly across some parts of our application,” McCormack said. “I wouldn’t say it’s everywhere yet, but we are starting to see that benefit of the Google power and the Google reach in terms of bridging traffic over their global fiber network.”
Right now, the company is still in the process of migrating the last of its users’ attachments to GCP. When that’s done, however, the company will be able to tell its users that all the data they have in the service is encrypted at rest, thanks to the capabilities of Google’s cloud.
From an Evernote standpoint, the company’s engineers have increased freedom to get their work done using cloud services. Rather than having to deal with provisioning physical infrastructure to power new features, developers now have a whole menu of options when it comes to using new services for developing features.
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