Desktop grids fall into two categories - local and volunteer. While local desktop grids are comprised mainly of a set of computers at one location, a business or institute for example, the resources in a volunteer desktop grid are provided by citizens all over the world.
Both local and volunteer desktop grids can provide a variety of different benefits. However their use raises a number of challenges:
Supporting a desktop grid: Aside from having to develop applications that can run across a number of independent computing systems, the distributed nature of a desktop grid poses unique problems. Volunteers provide their hardware to volunteer grids, which can be located around the world; so, it is difficult to fix and test applications on their machines.
Making it green: Desktop grids are often touted as a ‘green solution’ or a sustainable option as they use computing resources already in existence. However, in reality, determining whether a desktop grid is green, or not, is complex. How volunteers choose to donate their computing time plays a big part in this – adding on a CPU load/usage to a machine running at a low capacity doesn’t cost much energy, but using a computer that would otherwise be switched off does. Even the country a machine is running in can make a real difference. Connecting a computer in a hot country such as Dubai to a desktop grid is likely to take more energy to keep the machine cooler than in a more temperate country such as the UK.
Local policies: Desktop grids are subject to the local information, communication and technology (ICT) policies at the institute or organisation that is hosting the donated computer. For example, if a company chooses to switch off computers at night, this can affect the availability of the desktop grid.
Evolving hardware: Today increasing numbers of people are accessing the internet through new technologies such as mobile phones and tablets instead of computers. In the future this evolving situation could have consequences for the desktop grid concept as it currently stands.
Mobile technologies: With increasing numbers of people accessing the web using mobile phones and tablets instead of computers, the desktop grid concept as it currently stands may need to evolve.
You can find a full report on desktop grids here as part of e-ScienceBriefings - helpful jargon-free summaries of key reports and issues on European e-infrastructure. If you would like regular updates subscribe to e-Sciencebriefings at http://www.e-sciencetalk.org/briefings.php