Need of Service Portfolio itil:v3

Most effective way of managing all aspects of services through their lifecycle using appropriate management systems and tools and automate processes.

It is most critical management system used to support all processes and describes a providers service in terms of business value- correspond to markets terms, providing a means for comparing service competitiveness across alternative providers.

Articulates business needs and the providers response to those needs.

Basis of a decision framework, a service portfolio either clarifies or helps to clarify the following strategic questions:
Why should a customer buy these services?
Why should they buy these services from you?
What are the pricing or charge back Models?
What are our strengths and weaknesses, priorities and risk?
How should my resources and capabilities be allocated?
The service portfolio is the complete set of services that are managed by a Service Provider.
Ideally the Service Portfolio should form part of a comprehensive Service Knowledge Management System (SKMS) and registered as a document in the Configuration Management System(CMS).

Once a strategic decision to charter a service is made, this is the stage in the service lifecycle that Service Design begins architecting the service. The Service Portfolio should contain information relating to every service and its current status within  the organization.