The Metro/Global Copy function allows you to cascade a PPRC pair with a PPRC-XD pair such that the PPRC secondary also serves as the PPRC-XD primary. In this configuration, a primary and secondary pair is established with the secondary located in a nearby site, protected from primary site disasters. The secondary volume for the PPRC-XD copy could be located thousands of miles away and would continue to be updated if the original primary location suffered a disaster.
For additional information about Metro/Global Copy, refer to Metro/Global Copy.