How is a transactional file system different from a journaling file system?
Journaling file systems maintain metadata (and sometimes user data) by recording events in a log. In journaling file systems, an event is any single file operation. If power fails, the log is re-read and validated for errors. A transactional file system uses completely different architecture than a journaling file system. The transactional file system works from two meta-roots; the known good state and the working state. In a transactional file system, a “transaction point” is the atomic event where the working state is committed to the disk and becomes the known good state.
