Thin Clients

Another method of delivering a computing infrastructure that deserves mention is the concept of "thin client" networks. In a Thin Client network you would have one or two fairly powerful servers that would host the applications you required and a number of network attached and less powerful terminal systems (the 'thin' clients). The theory is that because the work is done on the host servers and the client systems are used primarily to drive the screen, keyboard and mouse then they can be built very cheaply. In addition to this, because they don't need to have a hard drive, diskette drive or CD Rom they should be more reliable. This type of setup can result in significant cost and maintenance savings, especially in larger networks where multiple systems of the same type are required, such as School or University computer labs. Because Linux provides robust multi user operation it is an excellent choice for the server operating system.

There are a number of ways to start taking advantage of the benefits of a thin client infrastructure:

• Move as many applications as you can to web-based delivery model and run them browser. In many cases this can be done without any changes to the clients. While this doesn't necessarily reduce the costs as much as other solutions, it does at least provide a way to consolidate your important data into one place. And of course, with a browser based application delivery model you have more choice with your client operating system. Linux is a good choice here in case you were wondering...
• Use older PC's as terminals. Successive versions of operating systems have traditionally required faster hardware thus forcing the purchase of new systems at a faster rate than may be desired. By using a thin client model, because the work is done at the server all the client needs to do is format and display the output. This extends the useful life of computer hardware while still delivering the required level of performance. In addition, because the clients can be loaded over the network there is no requirement for modern, high capacity hard drives.
• Using dedicated thin-client hardware. In theory the hardware can be made super-cheap, super-reliable and also much quieter/lower power usage than an ordinary PC. Some solutions incorporate this technology into the back of the screen or monitor further reducing the hardware footprint. If you choose to investigate these tyoes of solution you need to be careful about what open standards the hardware complies with and what systems it will interoperate with. It is pointless purchasing a dedicated thin client solution that only works with the vendors server system.

The Linux Terminal Server Project is one method used to deliver Open Source based thin client computing. LTSP is an add-on package for Linux that allows you to connect lots of low-powered thin client terminals to a Linux server. Applications typically run on the server, and accept input and display their output on the thin client display.

A project based on LTSP and designed specifically for schools is the K12 Linux Terminal Server Project. K12LTSP is based on RedHat Fedora Linux and the LTSP terminal server packages and it's very easy to install and configure. Once installed K12LTSP lets you boot diskless workstations from an applications server.