I pinched this excellent articule from Patrick Rouse :
http://www.msterminalservices.org/articles/Virtual-Desktop-Infrastructure-Overview.html
There are many advantages and some disadvantages to any VDI Solution, but some common usage scenarios are:
- Enterprise Desktop Consolidation – many organizations struggle with management of their client computers. Tasks like procurement of desktop computer hardware, deploying or patching desktop operating systems, updating antivirus signature, securing data, and desktop support become more and more challenging as the size of an organization grows, and the disbursement of employees across multiple locations increases. Replacing all or a bulk of an organization’s computer workstations with expendable thin client terminals and managing the client OS and applications in a centralized location is something most CIOs would love to be able to do.
- Remote Developer Support – as companies have outsourced all or some of their development efforts, some problems have arisen. How does one provide a remote application developer with a powerful, secure working environment, while protecting the parent organization’s source code and intellectual property. VDI addresses these issues by providing a remote developer with one or a group of virtual machines that can be used, rebooted, destroyed and easily rebuilt. Since the working environment is contained in the corporate data center, source code remains in the hands of the owners.
Advantages of VDI
- Reduced cost in purchasing desktop computers, as thin clients often last two to three times longer than a desktop computer
- Centralized Client OS Management
- Rapid Client Deployment
- Reduction in desktop support costs
- Reduction in electricity costs, as thin client computers use only a fraction of amount of energy that is used by a desktop computer.
- Improved Data Security
- Secure Remote Access, as most connection brokers offer an SSL VPN Component and Web Portal
- Compliance with HIPAA and Sarbanes Oxley (SOX)
- Fewer Application Compatibility Problems than with Terminal Server and Citrix, as users have their own, single user OS.
Disadvantages of VDI
- Many items that are problematic in Terminal Server and Citrix environments exist in VDI, i.e.:
- Printing often requires a 3rd party add-on
- PDA Sync not supported
- Scanning is not natively supported
- Bi-Directional Audio is not natively supported
- Display protocols not suitable for Graphics Design
- Requires low-latency connection between the client and virtual infrastructure
- Requires Enterprise Class Server Hardware and Storage Area Network
- For VMs permanently assigned to specific users, these machines need to be patched just like a physical client computer.
- Requires IT Staff skilled with VMware and terminal server. These are usually different staff, as the people using VMware are historically using it for consolidating servers, whereas those skilled with terminal server or Citrix are used to dealing with end user applications and devices. Although talk of VDI does not typically mention terminal server, every XP Pro or Vista Remote Desktop Host is a single user terminal server.
- Does not scale as well as terminal server, which often can host 25 to 100 users per dual CPU server. VDI will likely scale from 10 to 20 VMs per dual CPU server, depending on how each VM is configured.
Conclusion
Virtual Desktop Infrastructure acceptance is becoming more widespread every day. This was evident by the number of VDI sessions at the 2006 VMWORLD Conference, and the percentage of the 7000 attendees that flooded them. There is also no lacking in the number of vendors offering VDI solutions that work with VMware. The question will be which solution to choose, and which solutions still exist a few years from now. As usually happens, new technology causes a lot of companies to jump on the bandwagon. It usually takes a few years to weed out those with solid product and strategy that will continue to grow with the needs of their customers.