Making changes to Google’s search infrastructure is akin to “changing the tires on a car while you’re going at 60 down the freeway,” according Urs Holzle, who oversees the company’s massive data center operations. Google updates its software and systems on an ongoing basis, usually without incident. But not always. On Feb. 24 a bug in the software that manages the location of Google’s data triggered an outage in Gmail, the widely-used webmail component of Google.

Just a few days earlier, Google’s services remained online during a power outage at a third-party data center near Atlanta where Google hosts some of its many servers. Google doesn’t discuss operations of specific data centers. But Holzle, the company’s Senior Vice President of Operations and a Google Fellow, provided an overview of how Google has engineered its system to manage hardware failures and software bugs.

Read more at Data Center Knowledge: How Google Routes Around Outages.