You’ll notice that I’ve focused thus far on Linux distributions that include some form of thin client functionality. This isn’t just chance, it is in fact what I wish to focus on. Preliminary research revealed a multitude of difficulties that could arise when taking any solution mobile. Two of the main difficulties were maintaining hardware reliability in harsh environments, and concerns of overall power consumption; the caveat here being that any overall solution should have a modest enough electrical footprint to be able to operate off the grid for as long as possible. It seems clear then that there needed to be a mechanism that would make the machines we used hardier, as well as letting them consume less power.

You don’t have to have worked in tech support to know a user is likely to be experiencing either a hardware or software problem (That is, if the problem is not behind the keyboard). However, I have worked in a support role and so this helps give some insight into the exact problems that users may come up against. I won’t claim to have exact figures, but many software problems are actually down to individual machine configuration. A sensible method of solving this would be to control applications centrally, which also has the added bonus of preventing users doing damage to their computing environment.

Likewise, of the 5+ year old machines we administered, the main hardware culprit was a broken hard drive. Since this is one of the only components with moving parts it was always the first to go. Since machines in mobile environments cope with larger amounts of physical stress, being able to operate them without local storage would be a boon.

The natural solution to these problems is to use thin client machines. Thin clients operate with no local operating system or storage, and receive a very minimalistic operating system over their network connection, which is then stored in working memory (RAM). All operations a user executes are actually processed at the server-side, and relayed back to the user through the network. Because processing occurs remotely, this means that thin-clients themselves require very little processing power. In turn, this opens up avenues to install very simplistic, low-power, cheap devices as clients because their sole processing capability is that of relaying peripheral activity, and displaying the content a server asks it to [23].

The benefit to an organisation is that there is only one central point on which to maintain software functionality, and a whole fleet of ‘dumb’ devices that because of their simplistic and decentralised nature require very little care and attention. A well planned thin client network should have marginally higher rollout costs due to the specialised nature of the hardware, as well as vastly decreased costs over the life of a system due to the lack of investment that has to be made at the desktop level, the smaller number of staff needed to perform maintenance, and the hugely decreased energy costs [24].

Thin clients also have other technical advantages in the way they operate. Consider that ten users may open up a single application like OpenOffice Writer. On typical desktop machines, each node will instigate a process and dedicate local memory to this process. In a thin client scenario, the application is launched remotely and multiple memory spaces are allocated to this to serve each client. This technique is called shared memory and improves the efficiency is which organisations are able to use hardware [23].

That’s a very simplistic approach to describing the virtues of thin clients, but the bottom line is that they really fit our scenario down to a tee. By taking this approach we can concentrate on an appropriately specialised single server, and use fairly cheap client nodes. Overall power consumption will be lower, and reliability is likely to be guaranteed to a higher level (not least because there are no hard drives).

Most of the thin client implementations that we’ll be studying are built from the Linux Terminal Server Project (LTSP), which is a concerted effort to bring free and open source thin client functionality into a wide range of Linux distributions [25].

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