What is openMosix not useful for?:
openMosix lets a cluster of computers behave like one big multi-processor computer. However, it doesn't automatically parallelise programs. Each individual process only runs on one computer at a time. For example, if your computer could convert a WAV to a MP3 in a minute, then buying another nine computers and joining them in a ten-node openMosix cluster would NOT let you convert a WAV in six seconds. However, what it would allow you to do is convert 10 WAVs simultanously. Each one would take a minute, but since you can do lots in parallel you'd get through your CD collection much faster
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If what you need to do is take a single process and parallelise it across multiple machines, then openMosix is probably not the technology you're looking for.