The computer system disclosed herein provides an aggregated directory facility which can encompass the file contents of a large number of high capacity storage devices such as CD ROMS and which enables a user to deal those files as though they were in a single physical volume. An age based caching system...http://www.google.com.hk/patents/US5590320?utm_source=gb-gplus-share專利 US5590320 - Computer file directory system
