Five years ago, Microsoft still was not running some of its major services on its own Azure cloud. Since then, the company has made a concerted effort to change this situation and it’s closing in on being able to claim all its first-party services, including Office 365, Xbox Live and Bing services, are running on Azure.

There are a lot of reasons for any company, including Microsoft, to want to have all of its cloud services hosted on a common infrastructure. By doing this, Microsoft and others can more quickly build new products; adhere to specific compliance needs; take advantage of cross-cloud underpinnings like the Microsoft Graph APIs; scale more quickly; use its own Azure-hosted services as proof-of-concept examples for customers; and, last but not least, save money.

Microsoft committed a decade ago to moving Office 365 to Azure. Like Bing and Xbox Live, Office 365 has been running in Microsoft’s own datacenters but it wasn’t actually hosted on Azure. It’s still not completely on Azure, but it’s getting closer, officials acknowledged when I asked recently for an update.

In a statement attributed to Azure Chief Technology Officer Mark Russinovich, Microsoft says:

“Most of Microsoft 365 services, including Teams, SharePoint Online and Office online, as well as Xbox Live services run primarily on Azure infrastructure today. Mailbox storage for Exchange Online and Outlook.com is also in the process of moving to standard Azure infrastructure.”

I asked Microsoft for an update on this for a few reasons. First, I’d noticed a couple of fairly recent Microsoft blog posts that claimed Microsoft was running all of its services on Azure. I knew this wasn’t true a few years ago. But last year, I saw this claim in a June post about Teams on Azure:

“Azure is the cloud platform that underpins all of Microsoft’s cloud services, including Microsoft Teams. Our workloads run in Azure virtual machines (VMs), with our older services being deployed through Azure Cloud Services and our newer ones on Azure Service Fabric.”

When I asked, I got the progress statement I provided above.

The way Microsoft got its first-part services moved to Azure is a story I’d love to tell. Unfortunately, Microsoft doesn’t really seem to want to talk about it beyond offering a few emailed statements. (Maybe because officials would prefer to let most people assume all of its services already are on Azure? I’m not sure.)

As I noted in 2016, there has been an internal Microsoft effort called the “CloudOptimal” program that was chartered with getting Microsoft’s own services on Azure. The CloudOptimal program’s mission was to migrate and run all first party services on Azure. All new services, like Teams, Windows Virtual Desktop and the xCloud gaming service, were built from the get-go to run on Azure. But some legacy services — especially bigger ones like Exchange Online — were not and need to be migrated.

I found a few Microsoft employees with “CloudOptimal” references in their LinkedIn profiles. There was at least one internal CloudOptimal conference designed to train hundreds of Microsoft engineers on how to migrate to or architect first-party commercial services in Azure. (Hey, there was even a CloudOptimal t-shirt; it’s for sale on eBay — used, for $24.99.)

One Azure program manager explained in his LinkedIn profile his role in helping to enable Microsoft services to “virtualize their workloads and run on Azure” via the CloudOptimal program. According to his profile, “This effort has helped move the needle towards our long-term vision to converge Microsoft’s fragmented infrastructure, generate new capabilities for Azure, and provide reductions in COGS (cost of goods sold), impacting Microsoft’s bottom line across all 3 segments as reported in the quarterly earnings.”

Key pieces of Exchange and SharePoint still run on the Autopilot bare-metal systems for which they were designed, I’ve heard. The front end servers for these services are running on Azure in some cases in virtual machines, I hear. But more complex database and mailbox servers still aren’t there yet. Still… the decade-only promise of getting its own services all running on Azure seems like it’s finally close to happening.