Since the initial Office 365 subscribers, Microsoft 365 has evolved significantly to become the vast cloud service it is today. The Microsoft 365 Substrate, sometimes known as the Office 365 Substrate in older sources, is a collection of shared services and storage that handles much of the labor involved in this transformation.
The Substrate is most obviously the common search provider for Microsoft 365 and the framework used to host its data governance features. It was created to provide a single set of services and storage. It may be best viewed as a shared NoSQL storage layer for Microsoft 365 that holds local data and offers digital twins of external data, building on the adaptable data storage technology utilized by Exchange.
For Microsoft, it makes sense to consolidate everything into a single data layer that serves as the basis for the Microsoft 365 services. In semiconductor fabs, the substrate is the layer on top of which chips are constructed, which explains the name. The Substrate in Microsoft 365 might not be all that strong on its own, but without it, nothing else would be possible.
That does not imply that your data is kept in just one store. Microsoft has been working hard to enable a common query architecture across data lakes, where relational and non-relational — structured and unstructured — data is kept in its own formats without slow translation to a lowest common denominator service. This work can be seen in Azure, where Microsoft has been putting a lot of effort.
The hidden Microsoft 365 service
Oddly, there isn’t much documentation for a service as crucial as the Microsoft 365 Substrate. The Microsoft 365 roadmap does make note of it, but that’s about it. However, given that this is a core technology and does not have any user-facing features, it might be better if there isn’t any potentially confusing documentation and only outputs that we can use to manage our Microsoft 365 instances.
The Microsoft 365 Substrate operates like the productivity software equivalent of a data lake, hidden beneath the well-known Exchange and SharePoint services. It makes sure that content is stored, if not in its original form, then at least as a digital twin of the original, using familiar formats that can be accessed using well-known application programming interfaces. Newer services can benefit from Azure tooling that is native to the cloud for scaling and global reach, with data available from both the SharePoint and Exchange services provided by Microsoft 365.
The combination of technologies required to run such stores serves as the substrate in this case, acting as an intelligent link between the new and the established. The long-term goal is to integrate all Microsoft 365 data into a shared storage layer that serves as the platform’s foundation, similar to Power Platform’s Data verse. That is a difficult operation that will take some time to complete; it will probably be based on the Extensible Storage Engine used in Exchange and other Office servers.
What the Microsoft Substrate accomplishes, not how it functions, is what matters. The specifics of how it works won’t be discussed by Microsoft, but the company will discuss it and its aspirations for the service. You only need to be aware that it exists and that it functions. Next, you can utilize its output to control your users’ data.
The Microsoft 365 Substrate and complianc
Supporting compliance requirements is one of the Microsoft 365 Substrate’s more crucial functions. It offers a method for integrating several services employing Exchange mailboxes into a single search and index layer.
For instance, Cosmos DB, which offers a consistent, global, and nearly real-time manner for Teams to render conversations and channels, is the foundation around which Microsoft Teams chats are constructed. It’s great that Teams is a cloud-native service, and it’s great for Teams’ internal operations.
But what if you need to conduct an e-discovery search of those channels or need to halt any ongoing talks legally? Because it replicates all of a user’s communications into a mailbox and all channel messages into a group mailbox, the Microsoft 365 Substrate can be useful in this situation. Channels upload files to OneDrive and SharePoint.
When utilized with Teams, compliance software created for SharePoint and Exchange can operate by using mailbox copies rather than the original Cosmos DB data. The e-discovery tools in Exchange can now manage mailbox data, shutting down copies when a legal hold is issued. Then you can apply rules to the data, like removing communications after a predetermined period of time to guarantee that sensitive material is contained.
This would have been challenging to implement without the Microsoft 365 Substrate, needing additional Teams and Cosmos DB functionalities. That could have been a difficult process requiring a lot of engineering work and adding delay to a service that needs to be quick because Cosmos DB is a core component of Azure.
You don’t need to be aware that the Substrate is managing data that is being copied from one service to another. To target Exchange mailboxes and SharePoint stores with holds and other e-discovery tools, you only need to be aware of their locations.
The future of the Microsoft 365 Substrate
Microsoft has mentioned leveraging the Microsoft 365 Substrate as a base for machine learning to be applied to the many communication channels we use, allowing pertinent information to be revealed by some upcoming set of client tools, whether they are offered by Outlook, SharePoint, or the new Viva services. Although they will be familiar APIs and tools built over a next-generation common data layer, the tools we currently use will continue to be referred to as Exchange and SharePoint.
In order to create a consistent and coherent environment, technologies like the Substrate are crucial. Building a cloud service like Microsoft 365 from what were isolated servers is a time-consuming and difficult process. They then serve as a foundation for the service’s future development, reducing data silos between services and laying the groundwork for fresh machine learning-powered software and services. This service, which started off as a mechanism to transfer material from unfamiliar services to well-known locations and provided a new architecture for the entirety of Microsoft’s productivity platform, has an intriguing future.