There was a problem with this strategy, however. Unlike the seventies, when perhaps one or two departments in an organization could afford a mainframe, clusters were cheap, and so they popped up all over the place; one might find multiple clusters within a department. It's not uncommon that users find they need to access resources from different administrative domains (that is, clusters) -- in this scenario, each cluster has its own system image, defeating the purpose of the single-system image.