The AFS File System AFS serves as an example of the facilities typically available in a wide-area file system. Using a set of trusted servers, AFS presents to clients a location-transparent, hierarchical name space. The distribution of volumes across servers is an administrative decision. AFS uses access control lists for protection. For performance reasons the granularity of protection is an entire directory rather than individual files.
Users can be members of protection groups .
Access control lists may specify rights for both users and groups. AFS supports multiple administrative cells , each with its own servers, clients, system administrators and users. Each cell is a completely autonomous environment. But a federation of cells can cooperate in presenting users with a uniform, seamless file name space. 2.2 File Migration and Replication Wide area file systems provide a location transparent file name space.