Oracle VSS writer allows third-party requester applications to control the behavior of recovery and backup sessions.

Third-party requester applications use VSS API setBackupOptions or setRestoreOptions to pass an appropriate string to the writer. The writer uses getBackupOptions or getRestoreOptions to get the string set from the requester to perform the pre or post backup and restore actions.

• Running Writer Control Commands
  The writer control commands are applicable to all the restored components during the postrestore phase.
• Controlling Commands for Database or All Tablespaces Component
  The POST_WTRCMD=UNTIL_SNAPSHOT command instructs the writer to perform recovery to the snapshot creation time.