Fossil

''This is about the Fossil filesystem. For Fido/Opus/SEAdog Standard Interface Layer, see the all-caps FOSSIL. For the main format used by the Fossil version control system, see Fossil repository database.''

Fossil is a filessytem for Plan 9 (not from outer space, but from Bell Labs or User Space). It takes archival snapshots to preserve the state of the files at various points in time.

Links

 * Wikipedia article
 * Man page
 * Setting up Fossil