The Retransmission Problem
Sun RPC (and hence NFS) masks network errors by retransmitting each request after a timeout.
- Handles dropped requests or dropped replies easily, but an operation may be executed more than once.
Sun RPC has execute-at-least-once semantics, but we need execute-at-most-once semantics for non-idempotent operations.
- Retransmissions can radically increase load on a slow server.