Thinking back and remembering a time before Citrix purchased XenSource, the company purchased an OS Streaming company called Ardence.  Well check out this great article from Wilco van Bragt which details the advantages and steps necessary to use Citrix Presentation Server with the Ardence technology.  

Introduction 

Ardence's OS-streaming capabilities represent a significant step forward in the virtualization evolution. Using Ardence software, the complete operating system can be virtualized, providing many advantages in terminal servers environments. Citrix expert Brian Madden has previously published a white paper offering a conceptual view of Ardence in combination with Citrix Presentation Server. This white paper goes a step further, actually describing how to run Citrix Presentation Server with Ardence's OS-streaming software.

Ardence OS Streaming Basics

For those who have not read Brian Madden's white paper or who are not familiar with OS streaming, the following is a basic description of how Ardence OS-streaming works.

With operating system virtualization nothing is pre-installed or permanently loaded on the local device and no hard-disk drive is needed. Everything is run from the network using what Ardence refers to as a virtual disk (or vDisk). There can be private vDisks or shared vDisks. A private vDisk is used by one client only, just like a local hard disk. Depending on the rights assigned, the user can save information on the vDisks. Secondly, there are shared vDisks used by multiple clients at the same time. During usage, changes are saved in a special cache, but when the client is shutdown or restarted the cache will be cleared. In other words when the client is booting up it will use the default configuration available on the vDisk.

Shared vDisks are created by copying the image of one machine that is installed traditionally and then storing that mage as a file on the network. Ardence software assures that when individual clients boots each has a unique identifier in the infrastructure.

Private VDisks are of little interesting in terminal server environments, except that because you do not need hard disks there is an additional security benefit. But the standard VDisk is very interesting in a terminal server infrastructure.

Read the entire whitepaper, here.