This comes up from time to time and I recently briefed some internal call center folks on how to handle this question or concern when speaking to prospective SMB customers about Office 365. In general I like to refer customers to our Office 365 Trust Center at http://trustoffice365.com.
The Office 365 Trust Center is fairly comprehensive. There is a wealth of all types of information including commentary about datacenter location and geo-redundancy.
It is however somewhat intentionally vague as our policy is not to disclose all our datacenters.
The Where is My Data? page in the trust center elaborates:
Does Office 365 or Microsoft Dynamics CRM Online share information about where data is stored?
Microsoft has a regionalized data center strategy. The customer’s country or region, which the customer’s administrator inputs during the initial setup of the services, determines the primary storage location for that customer’s data. For specific details about where data is geographically located, see the information in the Data Maps table:
Why would Microsoft move data to a different region from my own?
The requirements of providing the services may mean that some data is moved to or accessed by Microsoft personnel or subcontractors outside the primary storage region.
For instance, to address latency, routing 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.
Where are Office 365 and Microsoft Dynamics CRM Online data centers located?
As a standard policy, Microsoft does not disclose the location of its data centers. Microsoft operates between 10 and 100 data centers located around the world.
The following are locations Microsoft has elected to disclose to the general public:
For customers who input a location in North America or South America (excluding Brazil) in the country or region drop-down box:
San Antonio, Texas
and other United States data centers
It is common knowledge and can be found online that we have a datacenter on the East coast and one currently underway in the middle United States as well. So at least 5 publically mentioned ones in the USA.
On the referenced page you can find out a few more details by viewing the North America Data Maps pdf file.. It is vague, but does state If you are a US customer your primary Datacenter is in the US and at least one backup datacenter is in the US. The country or region above is selected and we use a datacenter proximal to help address latency.
If prospects want to know more about our Datacenters I would refer them to www.globalfoundationservices.com. Everything we publically acknowledge is disclosed there. Virtual tours as well!
This information is usually enough to placate customers concerns. I would interested in hearing what your thoughts are on the subject.