What is the direction of data synchronization between primary and backup sites in SRM?

What is the direction of data synchronization between primary and backup sites in SRM?

The data synchronization in SRM is unidirectional, which means that when both the primary site and the backup site are normal, the primary site regularly synchronizes data to the backup site, but the backup site will not actively synchronize data to the primary site. Only when the primary site is destroyed and the backup site continues to provide services to the outside, the resulting data changes will be synchronized to the primary site when the primary site is restored.