Metro/Global Mirror adds FlashCopy® relationships to insure consistent point-in-time data at the remote recovery site.
Figure 1. Metro/Global Copy with optional FlashCopy
Also known as Cascading PPRC with Global Mirror, Metro/Global Mirror is a chained set of PPRC pairs, the first pair being synchronous PPRC and the second pair being a PPRC-XD pair that is part of a Global Mirror session managed by a master storage control. The master storage controls FlashCopy consistency group formation across the session at regular intervals.
For information on converting an existing cascaded configuration to a multi-target
configuration, refer to Converting to Multi-Target Mirror.