Metro Mirror and Global Copy are remote copy functions that replicate updates from one volume to another. Metro Mirror is a synchronous form of replication that mirrors data to the secondary volume before considering the host I/O to be complete. Global Copy is an asynchronous form of replication that copies data to the secondary volume at some time after the host I/O has completed.

Metro Mirror and Global Copy have many common characteristics. For those features that area common to both Metro Mirror and Global Copy, the more general term Peer-to-Peer Remote Copy (PPRC) is used.

The chapters in this part of the book provide an overview of Metro Mirror and Global Copy and describes these remote copy functions.