RPC based filesystem. Caching takes place both at file servers and at clients. Caches used to reduce disk-related delays and contention, network delays and contention, and CPU load on server.
Cache consistency is provided for both concurrent sharing and serial write sharing.
File cache and virtual memory share physical memory, and sharing ratio varies dynamically. Caches stored in local memory - allows diskless workstations, much faster than disk access, memories getting larger. This is so you don't have to traverse disk map metadata to locate cache blocks. 30 second delayed write-back. Tradeoff between performance and reliability in the case of a client cache.