Customer Success Testimonial: Recovery is Everything

The extreme email delays the plagued users of Google's Postini message management service earlier this week were caused by a shoddy email-filter update and a power-related hardware failure involving the company's database storage servers.

Today, the Mountain View Chocolate Factory released an "incident report" to Postini users, saying the "severe mail flow issues" began at 11:30pm Pacific time on Monday and extended through at least 12:30am Pacific on Wednesday. That puts the email snafu past the 24 hour mark.

"My company is on System 5 and our email was pretty much non-existent until we switched to a backup system. Once we pulled Postini out of the loop, all of that deferred mail hit our system (along with quite a lot of spam)," said Russ Meyer of the US-based Midland Paper.

At one point, Google rerouted traffic to another data center, which could explain the delays seen by Meyer.

Unlike so many on System 7, however, Meyer and Midland never had problems visiting the service's web-based admin console, which Google switched off for some customers in an effort to boost mail flow.

On Monday evening, after Google's monitoring systems detected the problem, engineers rerouted mail traffic from what the company calls a secondary data center. But this didn't help. So they returned some of the traffic back to the primary facility "to maximize processing resources." Then, at least for some users, they shut-off the admin console and some other web interfaces in an effort to reduce the strain on those resources.

Eventually, Google engineers decided the problem was down to three things:

• A new filter update appears to have inadvertently impacted the mail processing systems.
• Unusual malformed types of messages triggered protracted scanning behavior, and its interaction with filter update affected mail delivery.
• A power-related hardware failure with database storage servers reduced input/output rates. The latency in database access reduced our overall processing capacity.

Which sounds like two things to us. Surely, it's the service's duty to deal with "malformed types of messages" - whatever those are.

"The combination of these conditions resulted in high failure rates for mail processing and the deferral of new connections from sending mail servers," Google's report says.

On Tuesday evening, a day after the delays first hit, engineers replaced the faulty hardware - with help from the vendor - and at 11pm Pacific, Google says, database disk throughout returned to normal. Then, an hour later, Google removed the offending filter update, and according to company, mail processing was back on track.

Google continued to process traffic across both data centers for another hour. The company does say, however, that users may still experience delays. "Although mail processing was at normal speed and capacity, some users may have seen delayed messages continue to arrive in their inboxes. These potential delays occur when the initial or subsequent delivery attempt is deferred and the sending server waits up to 24 hours before resending the same message." This explains complaints we received on Wednesday afternoon.

The report says no messages were bounced or deleted.

Originally, Google indicated the problem was limited to US users, but yesterday, the company acknowledged that at least some European users were affected as well. ®

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