Architecting a vSphere Compute Platform : Software-Defined Compute and Hypervisor Concepts
   
Software-Defined Compute and Hypervisor Concepts
The software-defined compute platform for the VMware Cloud Provider Program is provided by the VMware ESXi™ hypervisor, which enables service providers to build an enterprise-grade, scalable, multitenant platform for complete compute service lifecycle management.
The hypervisor replaces the traditional operating system, such as Microsoft Windows or Red Hat Linux, and provides the ability to create a number of virtual servers on the same hardware. This technique provides multiple benefits, one of which is isolation of the virtual server from the underlying hardware, allowing hardware resources to be utilized more fully, and providing the mechanism for dense server consolidation that is the basis for enabling cloud-based computing.
Employing this VMware based software-defined computing layer gives the service provider the ability to seamlessly deliver highly-scalable, on-demand infrastructure services to consumers, while reducing power, saving space, maintaining reliability, and reducing the overall cost to serve.
While a virtual machine is a logical entity, to its operating system and end user, it appears to be a physical host with its own CPU, memory, network controller, and disks. All virtual machines running on a host share the same underlying physical hardware, but each consumes its share in an isolated manner. From the hypervisor’s perspective, each virtual machine is a discrete set of files that include a virtual machine configuration file, data files, and so on.
Figure 4. Hypervisor Architecture