Business demands change dynamically. A think through on how IT will meet the demands of this dynamic environment will lead you naturally to the contemplation of service based Cloud models—especially delivery of IT as a service (ITaaS). You will be forced to think out of the box and begin a journey that will convert the inflexible IT infrastructure of your organization into an agile infrastructure in the Cloud.
Virtualization is not a mere catalyst for consolidation of servers. It is the foundation of delivering IT services in the Cloud, the creation of a software defined data centre that goes beyond server consolidation and virtualization to encompass storage, networks and security resources of the organization. The software-defined data centre (SDDC) has been described as:
“The software-defined data centre is a unified data centre platform that provides unprecedented automation, flexibility and efficiency to transform the way you deliver IT. Compute, storage, networking, security and availability services are pooled, aggregated and delivered as software, and managed by intelligent, policy-driven software. Self-service, policy-based provisioning, automated infrastructure and application and business management complete the picture. The result is a data centre optimized for the Cloud era, providing unmatched business agility, the highest service-level agreements (SLAs) for all applications, dramatically simpler operations and lower costs.”
- Extracted from –Delivering on the Promise of the Software-Defined Data Centre 
Cloud infrastructures make organizations proactive. IT is made responsive and not reactive. Requests can be serviced almost instantly and wait times to service are almost negligible. Since infrastructure is abstracted, pooled and automated, IT managers can demand and obtain additional hardware or software to service any kind of demand that may arise in the course of a business. IT will be able to deliver appropriate levels of service even as the business requirements change or are modified by the economic and social environment in which it operates.
A CIO/IDG 2012 “IT Decision Makers Survey” revealed that nine out of ten IT leaders selected the SDDC for one of the following reasons:
- The Cloud improves agility of IT deployment and hence the business
- The Cloud helps cut costs
- The Cloud adds value to the business.
Other perceived benefits of Software defined data centre (SDDC) have been listed in various literatures as:
- Enabling rapid response
- Automating IT operations management
- Effectively enforcing Service Level Agreement (SLA)
- Eliminating vendor lock in
- Freeing IT staff for innovation
- Bringing in unmatched efficiency and resiliency
 – http://www.vmware.com/files/pdf/VMW_13Q1_BB_SDDC_020813_FINAL_LTR.pdf