Patent attributes
Embodiments are directed to managing data in a file system. An object from the file system that has parent objects may be provided. A snapshot in a current epoch may be generated such that the first snapshot may be based on the object and descendants of the object. A coverage set may be provided for the object that references the snapshot and also references each other snapshot that includes the parent objects. Read-only access to a version of the object may be provided based on a correspondence of the version and a snapshot referenced by the coverage set of the object. A coverage engine compares the update to a coverage update epoch (cue) associated with the parent objects. The coverage engine updates coverage sets of the parent objects based on grandparents of the object.