Single Tenant Vs Multi Tenant:
From an Exchange Admin perspective, We often come across the term “Multi Tenant” when Office 365 is discussed.
Many of us think that Cloud Offerings are Multi Tenant in nature and On premise models are based on Single Tenant all the time. This assumption is very wrong!
Let us explore further.
Assume that I am working as an Exchange Admin for an organization named msmessagingpro.com. The organization uses Exchange Server 2013 SP1. This company has two major LOBs as msmessaging and ldkmstech. The AD domain name is msm.com
- Half of the employees need to have an email address ending with @msmessaging.com
- Rest of the employees need to have an email address ending with @ldkmstech.com
In this case, I can create multiple Accepted Domains, Email Address Policies, Address Books and optionally add UPNs in the AD Domain & Trusts console to create Multi Tenancy in an On Premise AD & Exchange Setp.
In short, multiple organizational units or LOBs depending on a Single Exchange setup will result in the demand for creating Multi Tenancy even in an On Premise setup.
Let us conclude this way ….
If an Exchange or On Premise application serves a single organization or having a single accepted domain name will result in Single Tenant Setup. In other words, each customer will have a dedicated Hardware & Software setup.
If an application or Service supports multiple organizations and multiple domain names within the same Infrastructure, we call it a Multi Tenant Architecture. The hardware & Application Infrastructure will be effectively shared among multiple customers. This forms the core concept of Cloud Computing.
Microsoft Office 365 has a common infrastructure which is multiple datacenters spread across various geographies and a common application provided as a “Service” to all the customers. Hence Office 365 implements the concept of Multi-Tenancy.
- Hence any customer would have the email address or MS Online User ID ending with .onmicrosoft.com.
- Each customer tenant is considered more like an “Organizational Unit” with corresponding accepted domain and email address policy.
- Of course we can add “domain names” that an organization owns to its own tenant component. Each admin of the Office 365 tenant will have access only to his own tenant and no access to underlying hardware since Office 365 is a typical SaaS offering