When running in dry run mode (--dry-run command line option), the copytool will let the MDT believe the operation was performed.

For instance, if the command was to archive a file, the copytool will not archive the file, but the MDT will set the exists and archived hsm state for the file. If the file is released, it will be lost, since it wasn't actually archived. When restored, if the copytool is still in dry run mode, the file length will be 0 byte.