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Storing Customer Data in Microsoft Datacenters

Office 365 customers, known as tenants within the configuration, all share Microsoft’s global datacenter infrastructure, which is composed of hundreds of thousands of servers located all over the world.

Within the tenant, customer data is housed in a region, based on their location and settings, as shown from the drop-down box displays.


Microsoft replicates customer data automatically across at least two datacenters at any given time to minimize against losses during any failover.

When you choose a region, you can see what data is where (when at rest) between the zoomed view and the details in the right margin:


Microsoft operates over 100 datacenters globally and continues to open more datacenter regions for Office 365 for business services. That being said, not every datacenter is used to host Office 365 and its services, but they do add to the available capacity (storage) and other resources (memory and system processing power) to support customer demand and the associated usage growth.

Some of the planning around the new datacenters goes beyond the resource level needs alone. New datacenters are also put online in geographic locations to offer “in-region” data residency for core customer data.

As Microsoft defines it, “core customer data is a term that refers to a subset of customer data defined in the Microsoft Online Services Terms: Exchange Online mailbox content (email body, calendar entries, and the content of email attachments) and SharePoint Online site content and the files stored within that site, and files uploaded to OneDrive for Business.”

Existing customers that have this “core customer data” stored in an existing regional datacenter are generally not impacted when a new datacenter comes online, with the possible exception if the replication partners change. A new datacenter being brought online generally doesn’t introduce new features, functionality, or other offerings.

Where existing customers have specific data residency requirements, they will have the option to have their core customer data moved to the new regional datacenter as applicable.

When the tenant administrator first sets up the tenant for a given configuration, what is selected as the customer’s country or region, determines the primary storage location for that customer’s data with respect to Office 365 or Dynamics 365, specifically, as a rule.

Having said that, that are a number of variables that can affect that and the requirements of providing the services to the customer may cause it so that some data is “moved to or accessed by Microsoft personnel or subcontractors outside the primary storage region.”

One example of where this may occur is in a congestion situation, or to address other network latencies, be they temporary or an ongoing capacity strain. In a situation such as that, data may need to be copied to different data centers in different regions. In addition, personnel who have the most technical expertise to troubleshoot specific service issues may be located in locations other than the primary location, and they may require access to systems or data for purposes of resolving an issue.

Microsoft’s business rules about notifying customers if and when data is transferred to a new country are well defined. “If we expand the region where your data is stored into a new country, we will provide 1 month advance notice of the change and Microsoft will give notice if and when Microsoft changes the information about Office 365 and Dynamics 365 data maps referenced in the table above.”

When this type of notice needs to be made, it will be delivered to tenant administrators who have checked the “compliance notifications” option in the My Profile part of the online services portal.

When customers have a strict data residency requirement, they have certain options regarding their core customer data if it should be moved to a new region.

The table below outlines some of the more recent datacenter regions and their corresponding ties to prior datacenter regions.

Customers with billing address in Previous datacenter region New datacenter region Region available since Announcement


Asia/Pacific Japan December 2014 Office 365 blog

Australia, New Zealand, Fiji

Asia/Pacific Australia March 2015 Office 365 blog


Asia/Pacific India October 2015 Microsoft Blog


North America Canada May 2016 Office 365 Blog

United Kingdom

Europe, Middle East, Africa United Kingdom September 2016 Office 365 Blog

South Korea

Asia/Pacific South Korea To be determined Microsoft Blog


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