The just-released Windows 10 Anniversary Update will be the version Microsoft's biggest customers use to migrate their PCs.
Due to timing on the part of both Microsoft and enterprises, Windows 10's support cycles -- and old habits -- this week's upgrade, tagged as 1607 to mark year and month, will shoulder the responsibility as the version destined for deployment.
"[Anniversary Update] is the right version for enterprises [because] it's like the first service pack," said Steve Kleynhans, an analyst at Gartner.
Microsoft may have abandoned the term "service pack" -- a label for the intermittent updates composed of previously-released bug fixes -- but the moniker remains alive among IT professionals. Service packs marked milestones in each Windows edition's lifetime, and the first was considered the most important because it represented a more stable build from which the biggest bugs had been expunged. Many swore to await Service Pack 1, or SP1, in a new Windows release before daring to migrate from a predecessor. The initial release, the rule of thumb went, was too risky to roll onto corporate PCs.
Enterprises view 1607 as analogous to a Windows 10 SP1, in part because of its timing: Like many SP1 releases, this week's upgrade went live a year after the original.
"Enterprises used 1511 for testing," said Kleynhans about the November 2015 upgrade. "But 1607 will be what they roll out."
The reasons go beyond habit, however.
Microsoft discarded decades of practice when it accelerated development and release schedules for Windows 10, promising regular updates and upgrades to refresh what it's called its last operating system, rather than wait three or more years before debuting new features. But that tempo required new rules, particularly for support: Microsoft did not want to be handcuffed to older code.
For most corporate PCs, the former 10 years of support shrank to 12-18 months, the span between the designation of a version as ready for the "Current Branch for Business" (CBB) track and the appearance of that version's second successor on the CBB.
1607 just hit the "Current Branch" (CB) the track designed for consumers -- and designed to use consumers as testers -- but won't be okayed for the CBB until some future date, most likely four months from now, or in late 2016.
(Microsoft's one CBB designation since last year's launch of Windows 10 was in mid-April, when, five months after 1511 appeared on the CB, the same code was approved for enterprises.)
The once seemingly-rigid cadence of Windows 10 releases -- three a year, each separated by about four months -- has collapsed, so it will be difficult to forecast exactly how long 1607 will be supported. Microsoft intends to release two upgrades in 2017, with 1607 the only one for 2016.
With two slated for 2017, the second's designation for the CBB would mark the end of support for 1607. Depending on the timing of the pair of releases next year, 1607 will almost certainly be supported throughout 2017 at a minimum, and probably well be into 2018, perhaps as long as mid-year.
(Assuming releases in the spring and fall of 2017, 1607 wouldn't see support end until the later winter or early spring of 2018.)
As Kleynhans pointed out, that period -- 2017 and the first months of 2018 -- will be migration prime time for enterprises. " is the version for all of next year," he said, referring to the enterprise. "That's the version people will know."
But 1607 won't be the only version to be deployed by companies as they wend their way through the migration job. Because the support lifecycle of a particular edition, say 1607, is shorter than the average start-to-finish migration, some businesses will be required to start with one version, finish with another.
According to a recent survey done by VMware, enterprise IT administrators and managers said it takes an average of 18 months to complete a Windows migration (and a majority of those polled said they expected Windows 10 to take the same amount of time as past upgrades). That means even if a company began deployment in April 2017 with 1607, it wouldn't finish with that same build because it would wrap up around the end of 2018, months after 1607 dropped off support.
How that will work is unclear, as IT has not been forced to upgrade machines already on the newest OS at the same time it also migrated other PCs from an older edition. The last massive enterprise upgrade cycle was Windows 7, whose SP1 was the sole service pack (and so is still supported); by default, then, companies began and finished their move from XP to Windows 7 with SP1. Windows Vista, which admittedly gained little traction in the enterprise, had a pair of service packs; even so, the first received support for more than three years, from February 2008 to July 2011, enough time for a company, had it wanted to do so, to complete a full deployment.