A typical VMware vSphere datacenter consists of basic physical building blocks such as x86 virtualization servers, storage networks and arrays, IP networks, a management server, and desktop clients.

This physical topology of the vSphere datacenter is illustrated in VMware vSphere Datacenter Physical Topology.

VMware vSphere Datacenter Physical Topology
The VMware vSphere physical topology of the datacenter is represented by the physical building blocks consisting of storage networks and arrays at the bottom level, IP networks, server groups (each containing ESX/ESXi and virtual machines), a management server, and desktop clients.

The vSphere datacenter topology includes the following components.

Computing servers

Industry standard x86 servers that run ESX/ESXi on the bare metal. ESX/ESXi software provides resources for and runs the virtual machines. Each computing server is referred to as a standalone host in the virtual environment. You can group a number of similarly configured x86 servers with connections to the same network and storage subsystems to provide an aggregate set of resources in the virtual environment, called a cluster.

Storage networks and arrays

Fibre Channel SAN arrays, iSCSI SAN arrays, and NAS arrays are widely used storage technologies supported by VMware vSphere to meet different datacenter storage needs. The storage arrays are connected to and shared between groups of servers through storage area networks. This arrangement allows aggregation of the storage resources and provides more flexibility in provisioning them to virtual machines.

IP networks

Each computing server can have multiple NICs to provide high bandwidth and reliable networking to the entire VMware vSphere datacenter.

vCenter Server

vCenter Server provides a single point of control to the datacenter. It provides essential datacenter services such as access control, performance monitoring, and configuration. It unifies the resources from the individual computing servers to be shared among virtual machines in the entire datacenter. It does this by managing the assignment of virtual machines to the computing servers and the assignment of resources to the virtual machines within a given computing server based on the policies that the system administrator sets.

Computing servers continue to function even in the unlikely event that vCenter Server becomes unreachable (for example, if the network is severed). Servers can be managed separately and continue to run the virtual machines assigned to them based on the resource assignment that was last set. After connection to vCenter Server is restored, it can manage the datacenter as a whole again.

Management clients

VMware vSphere provides several interfaces for datacenter management and virtual machine access. These interfaces include VMware vSphere Client (vSphere Client), web access through a web browser, vSphere Command-Line Interface (vSphere CLI), or vSphere Management Assistant (vMA).