Image management, which is sometimes called disk image management, is the idea of creating a reusable copy of a virtual machine's hard drive. This is typically the operating system and any locally installed applications. The key concept behind disk image management is reusability, which allows us to deliver the necessary operating systems to most of the users using as few unique images as possible. By reusing a common image, we can save on the overall management (time to update, configuration changes, and so forth) as well as resources (the storage capacity and disk utilization.) This is a key reason why the use case design, as discussed in Chapter 2, Defining Your Desktop Virtualization Environment, is so important.

The image management concept

Citrix offers you two products as part of XenApp 7.5: Machine Creation Services and Provisioning Services. We will cover both of these in greater detail later in this chapter, but for now, we will focus on the larger...