Explanation for Gmail Outage from the Gmail Team

"Lots of folks are asking what happened, so we thought you'd like an explanation. This morning, there was a routine maintenance event in one of our European data centers. This typically causes no disruption because accounts are simply served out of another data center.

Unexpected side effects of some new code that tries to keep data geographically close to its owner caused another data center in Europe to become overloaded, and that caused cascading problems from one data center to another. It took us about an hour to get it all back under control.

The bugs have been found and fixed, and we're in the process of pushing out changes. We know how painful an outage like this is -- we run Google on Gmail, so outages like this affect us the same way they affect you. We always investigate the root causes of rare outages like this one, so we can prevent similar problems in the future." -- Gmail Site Reliability Manager

Update on today's Gmail outage [via]