Any given build, say No. 1, can be in use somewhere over a 16-month stretch.
And that doesn't even count Windows Insiders, who will presumably be on some kind of preview of Build 4 as it works its way to a December 2016 release to CB. "Insider is only beta testing and not for production," noted Gary Chen of IDC, essentially discounting the preview program from the forks discussion because of its limited appeal.
According to Microsoft, some five million users are now running Insider -- a paltry number compared to the 1.5 billion running some form of Windows -- but data from metrics firm Net Applications indicates that the number is half that, about 2.6 million.
Where Insider rings fit in
Complicating matters are the "rings" that Microsoft has used in the Insider program, and will replicate in the other branches. Through the months-long Insider, Microsoft has offered testers a "slow" ring and a "fast" ring, with the latter pushing updates more frequently, the former less often but with more stable code.
Microsoft has said that the CBB branch, and by implication the CB branch as well, will have rings of their own -- perhaps the same fast and slow of Insider -- so users have some choice about when they receive updates and upgrades. In May, OS head honcho Terry Myerson said, "There will be new rings specifically for enterprises, for businesses that want to be in slower rings to make sure all the kinks are worked out in any updates before it gets applied to their system."
Adding rings to the branches, assuming two rings per, doubles the number of different versions active at any one time.
Meanwhile, large organizations and corporations with volume licensing and Software Assurance agreements for the Windows Enterprise edition will assign significant numbers of systems to the Long-term Servicing Branch (LTSB), a static channel that will resemble the historical practice of letting the code be, updating only for vulnerability patches and critical repairs. A LTSB build can be run, Microsoft has said, for as long as 10 years, but interim builds will be issued to refresh that branch every two or three years.
The upshot is that there will be a lot of different flavors of Windows 10 out and about concurrently.
"We've at least got five rings ... the 'ring count,' if you will," said Wes Miller of Directions on Microsoft, ticking off the Insider fast, Insider slow, CB, CBB and LTSB. "So that's at least five milestones to track. Then you've got different states of each: Customer has applied the latest patches or hasn't applied the latest patches. So that's at least 10."
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