Human error root cause of November Microsoft Azure outage

The November 18-19 outage was caused by an update that Microsoft personnel assumed to be sound, but wasn't

Human error was the culprit for a November outage of the Microsoft Azure cloud storage service. The company is hoping that recent updates that automate formerly manual processes will help prevent similar outages in the future.

"Microsoft Azure had clear operating guidelines but there was a gap in the deployment tooling that relied on human decisions and protocol," wrote Jason Zander, Microsoft vice president for Azure, in a blog post Wednesday detailing the outage. "With the tooling updates the policy is now enforced by the deployment platform itself."

This is not the first time Azure has been bedeviled by human failure.

In February 2013, a lapsed security certificate led to a major Azure outage.

Both cases show how even small errors can have a huge impact in a service as large as Azure, and seem to have reinforced for Microsoft the importance of automating manual processes as thoroughly as possible.

This latest Azure outage happened late in the evening of Nov. 18, Pacific Standard Time (Nov. 19 Coordinated Universal Time), due to intermittent failure from some of the company's storage services.

Other Azure services that relied on the storage service also went offline, most notably the Azure Virtual Machines.

The outage stemmed from a change in the configuration of the storage service, one that was made to improve the performance of the service.

Typically, Microsoft, like most other cloud providers, will test a proposed change to its cloud services on a handful of servers. This way, if there is a problem with the configuration change, engineers can spot it early before a large number of customers are impacted. If the change works as expected, the company will then roll the change out to larger numbers of servers in successive waves, until the entire system is updated.

In the case of this particular change, however, an engineer assumed that the update had already been tested in a number of waves (or "flights" in Microsoft parlance), and so went ahead and applied the change across the rest of the system.

The configuration, however, contained an elusive bug that would cause the storage service software to go into an infinite loop, preventing further communications with other components of the system.

Microsoft engineers quickly pinpointed the problem and issued fixes. By 10:50 a.m. UTC, the storage service was completely back online, though restoring all of the virtual machines, a small number of which were isolated from the network due to the outage, would take another two days.

In the weeks that followed, Microsoft investigated in detail what went wrong, as well as looked into ways to make sure the outage wouldn't happen again. As a result, the company has updated its deployment system so that it now enforces the testing and flighting policies before new code or a change goes live across the entire system.

"With the tooling updates the policy is now enforced by the deployment platform itself," Zander wrote.

In the outage of February 2013, a failure in manual protocols was also to blame. Parts of the system went offline due to lapsed security certificates. The process to apply the updated certificates to Azure machines was scheduled with a larger routine update, a decision made by engineers who were unaware that the new certificates would not be delivered until after the old ones had expired.

After investigating the November incident, Microsoft wanted to share its "root cause analysis" with customers, Zander wrote, in hopes that users would find the act of transparency to be proof of Microsoft's commitment to providing quality cloud hosting services.

Overall, the act of posting of the root cause analysis seemed to please at least some Azure users and the IT community as well, despite the additional negative publicity it could bring Microsoft.

"I've seen several companies where analysis like this would be for management only. I guess it's just human nature to want to sweep mistakes and accidents under the rug, but it does also speak volumes about the culture in such companies. Kudos to Microsoft and every other big player that communicates these things," wrote a user on the Hacker News aggregation site.

Joab Jackson covers enterprise software and general technology breaking news for The IDG News Service. Follow Joab on Twitter at @Joab_Jackson. Joab's e-mail address is Joab_Jackson@idg.com

Join the Good Gear Guide newsletter!

Error: Please check your email address.

Tags Microsoftcloud computinginternetInfrastructure services

Our Back to Business guide highlights the best products for you to boost your productivity at home, on the road, at the office, or in the classroom.

Keep up with the latest tech news, reviews and previews by subscribing to the Good Gear Guide newsletter.

Joab Jackson

IDG News Service
Show Comments

Most Popular Reviews

Latest News Articles

Resources

PCW Evaluation Team

Azadeh Williams

HP OfficeJet Pro 8730

A smarter way to print for busy small business owners, combining speedy printing with scanning and copying, making it easier to produce high quality documents and images at a touch of a button.

Andrew Grant

HP OfficeJet Pro 8730

I've had a multifunction printer in the office going on 10 years now. It was a neat bit of kit back in the day -- print, copy, scan, fax -- when printing over WiFi felt a bit like magic. It’s seen better days though and an upgrade’s well overdue. This HP OfficeJet Pro 8730 looks like it ticks all the same boxes: print, copy, scan, and fax. (Really? Does anyone fax anything any more? I guess it's good to know the facility’s there, just in case.) Printing over WiFi is more-or- less standard these days.

Ed Dawson

HP OfficeJet Pro 8730

As a freelance writer who is always on the go, I like my technology to be both efficient and effective so I can do my job well. The HP OfficeJet Pro 8730 Inkjet Printer ticks all the boxes in terms of form factor, performance and user interface.

Michael Hargreaves

Windows 10 for Business / Dell XPS 13

I’d happily recommend this touchscreen laptop and Windows 10 as a great way to get serious work done at a desk or on the road.

Aysha Strobbe

Windows 10 / HP Spectre x360

Ultimately, I think the Windows 10 environment is excellent for me as it caters for so many different uses. The inclusion of the Xbox app is also great for when you need some downtime too!

Mark Escubio

Windows 10 / Lenovo Yoga 910

For me, the Xbox Play Anywhere is a great new feature as it allows you to play your current Xbox games with higher resolutions and better graphics without forking out extra cash for another copy. Although available titles are still scarce, but I’m sure it will grow in time.

Featured Content

Latest Jobs

Don’t have an account? Sign up here

Don't have an account? Sign up now

Forgot password?