If you are a hardcore Google user, you may have been tempted to pull out a few hairs last Friday as several of the company’s key services experienced a painful hiccup. Now, Google is shedding some light on the incident.
Specifically, Google users who use logged-in services like Gmail, Google+, Calendar and Documents were unable to access those services for about 25 minutes, according to Google vice president of Engineering Ben Treynor.
“For about 10 percent of users, the problem persisted for as much as 30 minutes longer,” he said on Friday. “Whether the effect was brief or lasted the better part of an hour, please accept our apologies -- we strive to make all of Google’s services available and fast for you, all the time, and we missed the mark today.”
What Really Happened?
Treynor reports that the issue has been resolved, and the company is now focused on correcting the bug that caused the outage, as well as putting more checks and monitors in place to ensure that this kind of problem doesn’t happen again. He then offered a technical explanation for what occurred and how it was fixed.
At 10:55 a.m. PST Friday morning, Treynor explained, an internal system that generates configurations -- essentially, information that tells other systems how to behave -- encountered a software bug and generated an incorrect configuration. The incorrect configuration was sent to live services over the next 15 minutes, caused users’ requests for their data to be ignored, and those services, in turn, generated errors.
“Users began seeing these errors on affected services at 11:02 a.m., and at that time our internal monitoring alerted Google’s Site Reliability Team. Engineers were still debugging 12 minutes later when the same system, having automatically cleared the original error, generated a new correct configuration at 11:14 a.m. and began sending it; errors subsided rapidly starting at this time,” Treynor said. “By 11:30 a.m. the correct configuration was live everywhere and almost all users’ service was restored.”
Will Google See User Backlash?
With services once again working normally, Treynor said work is now focused on removing the source of failure that caused Friday’s outage, and speeding up recovery when a problem does occur. Google then took three more steps:
(1) Correcting the bug in the configuration generator to prevent recurrence, and auditing all other critical configuration generation systems to ensure they do not contain a similar bug; (2) adding additional input validation checks for configurations, so that a bad configuration generated in the future will not result in service disruption; and (3) adding additional targeted monitoring to more quickly detect and diagnose the cause of service failure.
We caught up with Greg Sterling, principal analyst at Sterling Market Intelligence, to get his take on the outage -- and its resolution. He told us because Google has such a strong reputation as a engineering-driven company when something like this happens it's surprising to many people.
“Again, isolated events like this are not a problem and users will forgive the outage,” Sterling said. “It becomes a problem when a pattern develops. If this were to happen multiple times it would start to become a problem for Google. Gmail has become a very strategic product for the company and it's unlikely that Google will experience many more of these outages.”