ZPAQ is an open source command line archiver for Windows and Linux. It uses a journaling or append-only format which can be rolled back to an earlier state to retrieve older versions of files and directories (https://en.wikipedia.org/wiki/ZPAQ, http://mattmahoney.net/dc/zpaq.html).
This system is intended for incremental archiving and backuping Regions at GT.M (https://en.wikipedia.org/wiki/GT.M) database engine.