By using GAD, you can migrate the UR environment between primary and secondary sites to different primary and secondary sites while keeping UR pairs. If a volume connected to a host via NVMe-oF is used as a GAD pair volume, the procedures for migrating the environment described in this chapter are not supported. This chapter provides the UR environmental migration functions and procedures by using GAD. If you perform the planned outages of the storage systems during the environmental migration, see the section about planned outages during UR environmental migration using GAD. If a failure occurred during the environmental migration, see the section about disaster recovery during UR environmental migration using GAD.