Overview of Backup Termination

The following table shows the sequence of actions and events that are required for a backup operation to be terminated. For more information, see Overview of Processing a Backup Under VSS.

Requester action Event Writer action
The requester terminates the shadow copy by releasing the IVssBackupComponents interface or by calling IVssBackupComponents::DeleteSnapshots. None None
IVssBackupComponents is released by calling IUnknown::Release. BackupShutdown The writer handles the event with CVssWriter::OnBackupShutdown, which allows it to clean up any state related to the shadow copy set. If the backup operation failed—that is, it did not generate a BackupComplete event—the writer may also have to perform error handling. See Handling BackupShutdown Events for more information.


Because an IVssBackupComponents interface cannot be reused, and the destructor of the interface terminates the shadow copies, there is typically no reason to call IVssBackupComponents::DeleteSnapshots. This method is designed to be used in conjunction with error handling and aborting backups (see Aborting VSS Operations).