Last week, Microsoft declared changes to how it will deal out upgrades for Windows Server, a move prompted, one analyst said, by customers’ calls for a set release schedule — just as enterprises made the case for reliable Windows 10 and Office 365 release dates.

Microsoft, not surprisingly, couched it differently, with a manager calling the decision necessary so businesses can “innovat[e] quickly” by leveraging “new operating system capabilities at a faster pace.”

Whatever the ultimate motive for the modifications, the result should be familiar to IT administrators dabbling in Windows 10 or on top of recent news about Office 365. That doesn’t mean there aren’t questions. And answers.

What’s the schedule for Windows Server updates?? Spring and fall, annually, Microsoft said, implying that, like Windows 10 and Office 365 ProPlus, Windows Server would be refreshed each March and September.

Previously, Microsoft planned to update Windows Server 2016’s Nano installation option two or three times a year under a Windows 10-esque “Current Branch for Business” (CBB) release tempo. Until recently, that was also the professed cadence for Windows 10.

Why the shift? According to Microsoft, the decision was driven by “the accelerating pace of change.”

Some customers, said Erin Chapple, a Windows Server general manager, in a post to a company blog, wanted a fast iteration to new features in the operating system. “IT leaders frequently ask me how Windows Server is evolving to meet this new reality and how they can take advantage of new innovations at the pace their business demands,” Chapple wrote.

But that doesn’t make much sense: Before the scheduling announcement, Microsoft was already delivering multiple upgrades annually to Server in the form of the Nano option.

So what’s the real reason? Jim Gaynor, an analyst with Directions on Microsoft, acknowledged that customers drove the decision. But he argued that they told Microsoft it needed to solidify release dates, for the same reason enterprises pushed the company to put Windows 10 on a regular, known-release schedule.

“They told Microsoft, ‘We need a reliable cadence,'” Gaynor said, pointing out that the two-to-three-times-a-year updates were not nailed down. The helter-skelter schedule Microsoft hoped to use, with flexible release dates and builds shipped only when designated features were finished, was too iffy for corporate.

Those kinds of complaints triggered responses from Microsoft, which in turn had an interesting side effect: The company has been on a product release synchronization binge, with Windows 10 and then Office 365 ProPlus put on the same timetable. Now, add Windows Server to the mix.

“Starting this fall, we plan to deliver two feature updates per year, each spring and fall, aligning to the Windows and Office Semi-annual Channel release cycle,” Chapple said.

What gets upgraded? More than before.

Along with firming up the schedule, Microsoft announced that it will issue twice-yearly upgrades for both Nano installations and those configured as Server Core. Previously, only Nano was upgraded on a rapid cadence.

“Server Core will now be included in the Semi-annual Channel,” said Chapple. “Server Core is a ‘headless’ installation option of the operating system that includes all the roles and features needed to run datacenter servers and containerized traditional applications.”

In his post, Chapple summarized the revised Windows Server release blueprint with a table. Computerworld‘s version is below.

Computerworld

What about support? Has that changed too? Yes and no.

When Nano was upgraded two to three times a year, Microsoft said it would support just two consecutive builds: The latest, or “N,” and its predecessor, or “N-1.” When N was replaced its by successor, “N+1,” support for N-1 would dry up.

Under that regime and with a three-times-a-year upgrade pace, support could be as short as eight months. A twice-annual tempo might mean support lasts 12 months.

But like Windows 10 and Office 365 ProPlus, each Windows Server interim upgrade will be supported for 18 months, an increase of approximately 50%. That additional time, Chapple contended, will let enterprises “skip one of the semi-annual releases and wait to upgrade until the next release.”

Figure 1 shows the start and end dates for this fall’s upgrade.

Computerworld

Did Microsoft also change the labels it uses for Windows Server refreshes? Yes. In another move toward conformity, Microsoft revised the terminology for the Windows Server release “tracks.”

The new naming is easiest to understand with a table, like so:

Computerworld

The twice-a-year updates will be named Semi-annual Channel, matching, more or less, the nomenclature of Windows 10 and Office 365 ProPlus.

The traditional release model, with a new edition of Windows Server shipped every two or three years, remains in place but gets a name tweak. Previously called “Long-term Servicing Branch” (LTSB) to mimic Windows 10’s least-changing version, it’s now been dubbed “Long-term Servicing Channel,” or LTSC.

Windows Server 2016, which debuted last year, is the current LTSC. It will be supported using the standard 5+5 scheme, with five years of “Mainstream” support and another five years of “Extended” support. The former expires Jan. 11, 2022, while the latter is exhausted Jan. 11, 2027.

However, customers willing to pay for the privilege may receive support for six more years atop the usual decade, for a total of 16 years. The new licensing option, titled “Premium Assurance,” debuted in December. Depending on when the customer buys into the deal, each additional year runs between 5% and 12% of the current licensing cost.

When will Microsoft release the Semi-annual Channel upgrade for Windows Server? The company said the updates will ship in the spring and fall, but also dropped clues that March and September would be the designated months by using examples such as 1709 and 1803 as labels. (In Microsoft’s lexicon, releases for, among other products, Windows 10, are numbered as yymm. Those examples would correlate to September 2017 and March 2018, respectively.)

It’s unclear whether Microsoft will issue upgrades on the same days in September and March that are the most likely release points for Windows 10 and Office 365 ProPlus: Each month’s Patch Tuesday. If Windows Server follows suit, the first upgrade would appear Sept. 12, the next on March 13, 2018.

Figure 2 shows the first two releases and their support lifecycle lengths, and illustrates how support for the two overlaps for a 12-month stretch.