Multi-Tenant Data Architecture

Multi Tenancy is one of the influential factor in todays TECH world. There are so many sites to help us in knowing the concept and implement the same in our business . Following site offers  a good knowledge and guidance for  MTS

http://msdn.microsoft.com/en-us/library/aa479086.aspx

I would like to brief out few points given in that site .

• Three approaches to achieve multi tenancy , 1) Separate Database , 2) Shared Database and Separate Schema  and 3) Shared Database and Shared Schema . Each of this has its own merits and demerits . 
• Realizing Multi Tenant Data Architecture   , 1) Security Pattern , 2) Extensibility Pattern  and 3) Scalability Pattern.