New Protocols for Remote File Synchronization Based on Erasure Codes

Given two versions of a file, a current version located on one machine and an outdated version known only to another machine, the remote file synchronization problem is how to update the outdated version over a network with a minimal amount of communication. In particular, when the versions are very similar, the total data transmitted should be significantly smaller than the file size. In this paper, we present a new approach to file synchronization based on the use of erasure codes. Using this approach, we design a single-round protocol that is provably efficient with respect to common measures of file distance, and another optimized practical protocol that shows promising improvements over rsync on our data sets.