Infrastructure as a Service (IaaS) is defined as service that provides compute, storage, and networking resources to end users as building blocks for deploying operating systems and applications (workloads).

The availability zone is generally defined as a location (data center) which, while offering an availability SLA (for example, 99.9 percent uptime) to customer workloads, is a single fault domain. Major outage of such a location results in total disruption of the services running there.

The following figure represents a typical deployment model of the IaaS single availability zone offering.

 

A single management cluster is running management components of the cloud (vCloud Director) as well as management components of resource groups (vCenter Server instances and supporting systems). Each resource group is represented by a vSphere environment consisting of multiple clusters managed by a single vCenter Server. There can be more than one resource group to scale beyond the limits of one vCenter Server, but they are all located within the same availability zone.