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Not All Hosted Desktops are Equal (Part 1)

In our work to provide high performance Hosted Desktops we have found a number of key areas for comparison, all of which make a huge difference to end user experience.

We’ve tried to keep this article less technical so that those making choices about Hosted Desktops, and between hosted desktop providers can be better informed.

When choosing a Hosted Desktop provider the approach to support, resilience, uptime and security are also important, but are beyond the scope of this article.


What is a Hosted Desktop?

For the purposes of this discussion, and for a non-technical audience we’ll start with a definition.

A hosted desktop is as:

Windows Desktop


Users run traditional Windows Applications


Is Hosted in a datacentre


Screen, Keyboard & Mouse streams connect across the internet using a protocol.


Key Differences

The differences between Hosted Desktop providers is considerable, and there are three main areas that make a huge difference to the end-user:
  • Session Virtualisation or Full Virtual
  • The Protocol.
  • Graphics Acceleration.

We have divided this discussion into a number of parts, and in this part we look at the differences between session virtualisation and Full Virtual Desktops.


Session Virtualisation

For many years Terminal Services has been the most heavily deployed session virtualisation technology. Session Virtualisation shares the underlying Windows Operating System between all users on the system, with each user being presented with their own application windows.

Hosted Desktops provided from this technology therefore suffer from the constraints of the shared Operating System:
  • Users are unable to install their own software.
  • Some applications cannot run in this environment.
  • Application crashes often take offline the Operating System, affecting all users at the same time.
  • Security concerns, particularly where Operating Systems are shared between organisations.

Although these drawbacks do exist, Session Virtualisation can provide an effective way of delivering certain applications to windows desktops (a number of accounting and database applications work well in this way).

Three main vendors provide Session Virtualisation Services:
  • Microsoft Terminal Services has been updated and is now called RD Session Host (RDSH) which also provides RemoteApp for access to single applications.
  • Citrix XenApp.
  • VMware Application Access has recently been added as part of their Horizon Workspace suite.


Full Virtual Desktops

The constraints of a shared Operating System can be overcome by virtualising the operating system and providing a separate Windows Operating System for each user which guarantees that:

  • Only the user whose application or system crashed will be affected.
  • Users can be granted rights to install their own software.
  • Security is enhanced.

Full Virtual Desktops also deliver much more flexibility for smaller companies as customisation and controls can be amended as required.

The first large-scale Full Virtual Desktop provider was VMware, who built on their leading Virtualisation Hypervisor platform to support desktops with their View product (which has been recently expanded and changed name to VMware Horizon).

Citrix followed with XenDesktop which built on the XenServer Hypervisor platform, and Microsoft has followed with RD Virtualisation Host (RDVH) from Server 2008 R2 which uses Microsoft’s HyperV technology.