Coda is a distributed file system developed as a research project at Carnegie Mellon University since 1987 under the direction of Mahadev Satyanarayanan.
It descended directly from an older version of Andrew File System (AFS-2) and offers many similar features.
Coda uses a local cache to provide access to server data when the network connection is lost.
Upon network reconnection, the client moves to reintegration state; it sends logged updates to the servers.
These unique features introduce the possibility of semantically diverging copies of the same files or directories, known as "conflicts".