Virtual Appliances
Virtual Appliances are a new way of deploying applications and infrastructure components, on virtualization technologies like VMware, Xen, Virtual Iron and Microsoft Virtual PC.
Virtual AppliancesTM are the smallest possible Operating System installation, optimized for the virtual environment, and running minimal applications, but with a supporting cast of a web user interface, a web services API, connections to shared storage, private firewall and zero configuration browsing.
The Virtual AppliancesTM foot print is nano-sized. This saves valuable resources on your shared storage infrastructure and resources on your virtualization hardware, where a virtual appliance consumes minimal memory and minimal IO bandwidth.
Though the motivation to move to a virtualized environment is to reduce cost of operation, the fact is that the machines hosting virtualization and shared storage are expensive. Virtual Appliances increases operational efficiency by having the smallest possible foot print, on disk and in memory.
Each Virtual Appliance type will run a single application, or a suite of applications to provide an infrastructure solution.

