In this article, I presume that you already know the basics of thin client setup: what is a thin client, [what is a terminal server](/tools/: http:/www.brighthub.com/computing/windows-platform/articles/30819.aspx), why do you consider deploying thin clients, does your business model support using thin clients, will your physical network infrastructure be able to carry the load, etc.. If you are done with this and have decided on implementation, then following is a structured approach to thin client migration.
Server and License Acquisition
Considering your physical network infrastructure can handle the load, then there are three things left to plan before deployment:
- Selecting the operating system: Throughout the article I assume Windows Server 2003 will be used.
- Selecting the server hardware: Depending on the number of users and the programs used, you have to select the server hardware. For light-load users, such as Office Suite and SAP users, you can deploy one terminal server for every 25 users as a rule of thumb. After that you will face performance bottlenecks either in the physical network or server load. And per 100 users, think about one node of failover cluster.
- Licence acquisition: There are two licenses for terminal servers: Per User or Per Device Client Access License (CAL). Considering the increasing use of mobile devices, netbooks, etc., I recommend Per User CAL.
Preparing the Terminal Server
After you add the terminal server role to Windows 2003 and you have the inventory of your current applications, then you can start preparing your server. Connect your server to your existing network and start installing applications, such as Microsoft Office and any line of business (LOB) software you are using (if you have come this far, you already have an inventory of your LOB applications, have ensured that you can run them on the terminal server, and verified that they have multi-user support).
Before rollout, select a couple of users for testing purposes. Personally I tend to select users who are tech-savvy and who are using different LOB applications. You will receive a lot of feedback from the techie users and have a very good troubleshooting base for the final rollout. Then, copy the user profiles from their current computers to the terminal server. It will be a nice idea to tell the users to place all their documents in their “My Documents” folder and tell them explicitly that whatever left in other folders may be lost forever. Create user profiles and copy their “My Documents” folder in their profiles (make them feel at home as much as you can). Ask them to login to the terminal server and start working there.
Allow yourself at least one month for testing with these users: don’t forget to make tests on out of office connections, different operating systems (Windows Vista, Windows 7, Linux, Mac), running all the applications at once, and torturing the system to the maximum extent. Document every single thing that you come up with! I know that you will complain about your boss pressing you to do the thin client migration immediately. The best thing to do is let him know about the costs of downtime if you go without proper testing. When bosses realize that they will lose money, they tend to take one step back.
Preparing for Failover and Load Balancing
Don’t forget to make plans about failover scenarios. As I have mentioned before, make sure that you have one empty failover node for every 100 users. Terminal services are highly sensitive: if one server fails, then everybody using that server will be logged out and will not be able to work. You have to take these users immediately to an empty node.
Consider Storage Area Network, File Server scenarios for storing user data and make them available independent of the terminal server. If one active node fails and the users failover to the empty node, they still should access their documents. I have to mention that Windows Server 2008, especially the R2 release has addressed Load Balancing and Terminal Server Farms very nicely. I can safely say that the Server 2008 release is worth the investment.
When you are rolling out the use of thin clients with your Windows Server 2003 infrastructure, make sure that you roll out the system slowly. First, introduce the system to the low-load users (Office Suite, ERP users etc.). When their problems are solved to a certain degree, begin rolling out to the high-load users, who use demanding applications and put heavy loads on the terminal servers. Try to balance high-load and light-load users on each terminal server to optimize the use of hardware resources.
Again, don’t forget to document. I strongly advise administrators to install a knowledge management application and to update it with every issue, request, problem and incident that is solved. And make heavy use of Visio (or Kivio, Dia depending on your preference) to visualize your network, servers and applications.