>after I start space reclamation and try to cancel this process, it seems
>that i can not completely wipe it out.

Reclamation process, cancel             The cancel will take effect when it
                                        reaches a point to safely stop the
                                        reclamation.  The system will finish the
                                        last process started, and once it is
                                        complete, stop.

  Richard Sims, BU