Update Propagation

The technique called operation based update propagation is for efficiently transmitting updates to large files that have been modified on a weakly modifications are captured above the file-system layer at the client, shipped to a surrogate client that is strongly connected to a server, re-executed at the surrogate, and the resulting files transmitted from the surrogate to the server. If re-execution fails to produce a file identical to the original, the system falls back to shipping the file from the client over the slow network. The prototype of this mechanism have been implemented in the Coda File System on Linux, and demonstrated performance improvements ranging from 40 percents to nearly three orders of magnitude in reduced network traffic and elapsed time. A novel use of forward error correction is also found in this context.