(Oversimplified most-frequent case)
Clients make requests for a file as if it were local. afsd
sees them and looks in the local cache. If the file isn't
there, it asks any of the servers that have that file in ro
path, starting with the one it favors. It caches the file
locally and makes it availble.
When a new version of the file is released, the servers issue callbacks to the clients that have the file, advising them that they need to obtain a new copy. The next time the file is accessed, the client discards the version in cache and obtains a new one. Callbacks are on a per-volume level for read only volumes, and a per-file level for read-write ones.
Unlike NFS, AFS is stateful. Also unlike NFS, it can be redundent so if a server goes offline it isn't the end of the world - most users won't even notice.
| previous | index | next |