Microsoft 365 File Storage Sources and Sinks

Many Microsoft 365 services use file storage, but their licenses do not offer any storage space of their own. The accompanying diagram shows common licenses that earn organizations Microsoft 365 file storage space (“Sources”, at left) and some Microsoft 365 services that consume that space without contributing any (“Sinks”, at right). 

Most SharePoint storage comes with Microsoft 365 E3 and E5, Office 365 E3 and E5, and SharePoint Online Plan 2 User Subscription Licenses (User SLs). These sources add 10GB per user to a tenant-wide, shared storage pool, which starts with 1TB before any licenses are assigned. The pool is subdivided by SharePoint site collections (top-level sites), each of which can reach a maximum of 25TB. However, an organization can create thousands of site collections, so the maximum pool size can grow into the petabytes if an organization can distribute users across site collections to scale up.

Each user assigned one of these licenses gets 5TB of file storage space for the user’s OneDrive for Business site. An organization can expand any user’s space up to 25TB at no charge. However, organizations are prohibited from using OneDrive accounts for shared storage. They may not, for example, archive all of their SharePoint sites into the OneDrive for Business site of a service account.