Andrew File System
AFS is a distributed file system with a common name space Based on a client/server architectural model, it allows one or more clients to access files made available by one or more file-servers./p>
Like the Unix file system, AFS uses a hierarchical tree structure for files. By convention, the root directory of the file system is identified by /afs, while the subdirectories of the root define the cells of the AFS file system. A cell is an administrative domain in the AFS space to which the set of clients and servers belong.
A caching mechanism, which is active on each client, allows for faster file access, taking care of maintaining a copy of the files in use on a local disk on that particular host.
Disk space on AFS file servers is organised into volumes, containers of files and directories made available to the user as a subdirectory of the AFS tree. Each volume has a quota assigned by the local administrator, which defines the maximum amount of disk space a volume can hold. Each user’s home directory in the infn.it cell resides on a different volume.
From the user’s point of view, the distributed nature of file system, volumes and the caching system, is absolutely transparent, since references to servers and, therefore, to the physical location of the files are not visible. Starting with the /afs root directory, the user will see the same directory structure on all AFS clients. In the Rome Section INFN, a user with an AFS account can publish personal web pages accessible in the standard way http://www.roma1.infn.it/~$USER or http://www.roma1.infn.it/people/$USER.