Coda is an experimental distributed file system, developed at Carnegie Mellon University since 1987, under the direction of M. Satyanarayanan. It is based on the older AFS, a similar but less advanced distributed file system.

Major features include:

  • Disconnected operation - Disconnect from the file server and carry on working
  • Client-side caching - Improves performance by reducing the need to fetch data from the server
  • Replication - Store and manipulate the same data on multiple servers, to improve reliability and scalability
  • Security - Uses a security system derived from Kerberos
  • Well-defined semantics of sharing, even with network failures

Coda is still under development, and the emphasis appears to be on moving from a very good research project to a useful filesystem ready for large-scale production use.

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