Google blames miscalculation for Gmail outage

by Stevie Smith - Sep 2 2009, 15:15

If you’re a Gmail user flummoxed as to why account access has been denied in the last few hours, you’re not alone in your plight. Moreover, according to Google, the majority of its Gmail user base has been forced to go without after the popular e-mail service was knocked offline on Tuesday.

Affecting both personal and business Gmail account holders, the sudden outage lasted for approximately two hours and left tens of million of users without access to Google’s service, which is the Net’s third biggest e-mail client and boasts around 150 million users worldwide.

During the short but annoying disruption, Gmail users attempting to access their accounts were left staring at a cursory error message that offered no concrete explanations in outlining that the login was “Unable to reach Gmail”.

According to Google, the outage was likely caused by a system load miscalculation connected to a number of Gmail servers that were taken off the grid in order to perform routine maintenance.

“As we now know, we had slightly underestimated the load which some recent changes (ironically, some designed to improve service availability) placed on the request routers – servers which direct web queries to the appropriate Gmail server for response,” said the search giant on its official Gmail blog.

“At about 12:30 p.m. Pacific a few of the request routers became overloaded and in effect told the rest of the system ‘stop sending us traffic, we’re too slow!” explained service reliability czar Ben Treynor.

“This transferred the load onto the remaining request routers, causing a few more of them to also become overloaded, and within minutes nearly all of the request routers were overloaded,” he added.

The search giant has since outlined that it countered the problem by increasing system capacity, and it hopes the revised capacity calculations will help prevent similar outages in the future.

This week’s blip in Gmail service follows a short outage in May when millions of account holders were deprived of access after an excessive flow of traffic was mistakenly routed through computers in Asia, which buckled under the pressure.

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