The Prospero file system is based on the Virtual System Model.
It differs from traditional distributed file systems in several ways. In traditional file systems, the mapping of names to files is the same for all users. Prospero supports user centered naming: users construct customized views of the files that are accessible. A virtual system defines this view and controls the mapping from names to files. Objects may be organized in multiple ways and the same object may appear in different virtual systems, or even with multiple names in the same virtual system.
Prospero directories can contain references to files and directories that are stored on remote nodes. This allows distribution at a much finer level of granularity than is possible in traditional distributed file systems. Prospero also provides several tools to support customization. Among them are the union link and the filter.