Vector time pairs are a new method for tracking synchronization metadata. A vector time pair consists of two vector times: one tracking ï¬le modiï¬cation history and one tracking ï¬le synchronization history. Because the vector times are maintained separately and used for diï¬€erent purposes, diï¬€erent algorithms and optimizations can be applied to each. As a result, vector time pairs impose no restriction on synchronization patterns, never falsely detect conï¬‚icts, require no space to store deletion notices, require network bandwidth proportional only to the number of ï¬les changed, and support partial synchronizations. No other current synchronization method has all these properties. Results from an implementation of vector time pairs in a new user-level ï¬le synchronizer called Tra conï¬rm the beneï¬ts of vector time pairs.
Previewing from http://publications.csail.mit.edu/tmp/MIT-CSAIL-TR-2005-014.pdf