How Microsoft's Azure organization makes the Windows sausage

Microsoft Azure Executive Vice President Jason Zander discusses how he's looking at his world now that it includes Windows engineering.
Written by Mary Jo Foley, Senior Contributing Editor on

Microsoft Azure EVP Jason Zander

Almost two years ago -- in March 2018 -- Microsoft reorganized its Windows business simultaneously with the departure of former Windows and Devices chief Terry Myerson. Organizationally, the company split Windows in two, with half the team moving into the Azure organization and the other half going to Experiences & Devices (E&D). The split basically was along the lines of the Windows stack, with the core of Windows going to Azure and the front-end UX going to E&D. Since then, Microsoft has said very little publicly about what that move has meant to how Windows is built and maintained across the various platforms it supports .

But this week, I had a chance to talk to Azure Executive Vice President Jason Zander about how he's looking at his world now that it includes Windows engineering.

(This post doesn't cover what's going on with the UX side of Windows which, organizationally, is in Executive Vice President Rajesh Jha's organization. Nor does it touch on the Essential Products Group (EPIC) work happening under Corporate Vice President Joe Belfiore. Belfiore oversees the Windows shell/user experience work, plus Microsoft Edge, News, OneNote, Education products, mobile apps and services on Android and iOS.)

Zander, who has been with Microsoft since 1992, leads the core teams working on Microsoft's intelligent cloud and intelligent edge products and services. He is in charge of Azure strategy, product management, engineering and operations of Microsoft's cloud product lines, SQL Server, big data and analytics, quantum computing and more.

As part of his purview, Zander also is in charge of COSINE, Microsoft's Core Operating System and Intelligent Edge team. (Microsoft does not share org charts, but I believe COSINE is run by Corporate Vice President Roanne Sones on the PM/platforms side and Corporate Vice President Michael Fortin on the dev side.) 

COSINE includes the former Windows and Devices Group (WDG) team, but it is more than just Windows engineering, as its name reflects. It also includes Microsoft engineers working on Linux, Windows Server and Azure, Zander said.

"We have some sophisticated kernel developers in Linux and Windows and Azure," Zander said. And given that Zander has some code which he wrote included in Windows 2000, "I've known these folks for decades," he said.

Before his departure in 2018, Myerson was in charge of the bottom of the Windows architectural stack (including the kernel, core, hypervisor and more) and also the Windows client PC business. Zander, at the time, owned Windows Server and Azure.

"We took the tech core of Windows and brought it to the Azure team," he said. "The core is now inside the organization instead of outside of it." And along with the technological Windows core that came to Azure came the lessons the Windows team had learned in building, testing and maintaining Windows at massive scale (900-million-plus Windows 10 PCs and counting).

COSINE is in charge of the OS platform foundation that works across Windows client, Server and Azure. It's in charge of the Windows source code and the hundreds of variations of Windows that the company builds daily.

COSINE also is in charge of the core host for Azure, Zander says, noting  he moved the Azure Compute team core into COSINE. That means the COSINE team is "now on 24 X 7, 365 days a year, for running a fleet," Zander said. In addition to patching and providing security without disruption for Windows via Windows Update, "they now also have a direct responsibility for the cloud."

Accordingly, the core Windows team has learned about what it means to be always on-call at a global scale. But the Azure folks also learned a thing or two from the Windows team, Zander noted.

"Any time you have a tech group managing over a billion PCs, there's amazing scale in terms of building, patching and releasing software," he said.

The core Windows team had built out "awesome telemetry and devices," Zander said. The Azure core team was able to take Windows' best practices and tools and apply them to managing the Azure fleet and to manage IoT systems, he said.

At the same time, the Windows core team had done and continues to do a lot of work on customizing Windows for new devices, like Surface tablets and PCs, Xbox consoles, HoloLens and -- in the coming year -- dual-screen devices like the Surface Neo. (This is where Windows 10X fits in.) The Azure team builds a lot of its own hardware designs. So that provided another opportunity for cross-pollination, Zander explained.

As I've written in the past, the Azure team is on a "semester" development schedule. Their semesters are codenamed using the periodic table of elements. The team's semesters run from January to June and July to December. (These semesters also align, coincidentally or not, to Microsoft's fiscal year, which runs from July 1 to June 30.) The 20H1 development semester is codenamed "Vibranium" (a placeholder name for "Chromium," which likely would have created a lot of confusion) and the 20H2 semester, "Manganese." 

In joining the Azure organization, the Windows development team came to adopt the same semester schedule, Zander confirmed.  The team is believed to be very close to finalizing the Windows 10 20H1 release, even though it won't start rolling out to mainstream users until the spring of 2020

Before the March 2018 reorg, the Windows team used to "ship" a finished version of Windows to the Azure team. That's not how things work anymore, Zander said. These days "the Windows core team of architects is involved in planning and ownership of the Azure cloud" from the get-go, he says.

"The Azure team is a systems team for Microsoft. That means we don't have a bunch of different teams doing different operating systems" or forks of operating systems, Zander said. 

Different organizations inside the company weigh in on Windows core priorities they need met during a given timeframe. This isn't something new, Zander said. Even when Windows and Azure were separate, Microsoft still had the issue of figuring out which features would be included in which Windows releases on behalf of each team. Sometimes gaming had top priority. Other times, a new Surface form factor would get top priority regarding which features they wanted and needed in a given Windows release.

"Security, reliability and performance are prioritized all across," Zander said. "Then certain features are prioritized depending on new launches -- like a new console launch."

Feature priorities are decided sometimes in a six-month or a year-long boundary, he said. The biggest take-away: "It's not a tyranny of organizations anymore" when it comes to deciding on timing and feature sets.

Given how high priority and all-encompassing Azure is for Microsoft these days, do Zander and his team still care much about Windows?

"I get updates every other day with self-host builds," Zander said. "We love Windows and will continue to love Windows."

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