In many cases, clustered applications will automatically detect the return of failed paths, and those applications will also come back online. In other cases, a host-level SAN scan may be required, or applications may need to be brought back online manually.

It depends on the application and how it's configured, and in general such tasks can be easily automated. SnapMirror active sync itself is self-fixing and should not require any user intervention to resume RPO=0 storage operations once power and connectivity is restored.