Reduces network traffic by retaining recently accessed disk blocks in a cache - repeated accesses to the same information is handled locally:
- If needed data not already cached, a copy is brought from the server to the user.
- Accesses are performed on the cached copy.
- Files identified with one master copy residing on the server machine, but copies of (parts of) the file are scattered in different caches.
- Cache-consistency problem – keeping the cached copies consistent with the master file.