Within an IaaS environment, customers can acquire one or more servers. As shown in FIGURE 4-13, these servers fall under one of three types:
Physical server: actual hardware allocated for the customer’s dedicated use
Dedicated virtual server: virtual server allocated to the customer, running on a physical server which may, or may not, have other virtual servers
Shared virtual server: customer access to a virtual server on a device that may be shared with other customers
An IaaS physical-server solution allocates one or more physical servers to the customer. The servers will not be shared with other customers. The physical server, because it is not shared by others, will be more expensive. However, the customer will have complete control over the system.
A dedicated virtual-server solution allocates to a customer one or more virtual servers, which, as discussed in Chapter 8, “Virtualization,” run on a server that has special software installed to be able to run multiple operating systems (which do not have to be the same). Each operating system is protected from others on the server and can often be configured by the customer. The virtual server is used by only one customer which, again, will result in a slightly higher cost per month.
A shared virtual-server solution allocates a shared virtual server to a customer. The server may, for example, provide web-server capabilities to multiple users. The customer cannot configure the shared-virtual server.