Physically dispersing an operating system

Computer systems can be &distributed& in many different senses - for example: the user access (such as remote terminals); the system geography (such as a computer network); the processing (such as a multiprocessor or a multicomputer); the data (such as a partitioned or a replicated database); the operating system (such as a network OS or a decentralized OS). These senses of distribution are not independent, and each has its own advantages and disadvantages in various circumstances, as well as its own research problems. However, some senses are becoming better understood than others, and some are becoming recognized as more fundamentally important than others. Distributing the user access or the system geography per se can be regarded as neither especially challenging nor critically fundamental technology. Distributing the (user portion of the) processing is important, and the ease of doing so is, to a first order approximation, determined by the extent and manner in which the data and operating system are distributed. It currently seems to be these latter two aspects of computing whose distribution involves the most essential, and difficult, new technology.