This part of the book describes multi-site configurations, including Metro/Global Mirror, which is a 3-site disaster recovery solution, Multiple Target Peer-to-Peer Remote Copy (PPRC) and z/OS Metro/Global Mirror.

Many companies and businesses require their applications to be continuously available and cannot tolerate any service interruption. A loss of a disaster recovery site is often considered to be a severe impact on their business. If their local production site fails, swapping to a Metro Mirror target allows applications to continue running. However, without another site to act as a backup for disaster protection, business applications are left unprotected from a subsequent failure or from a disaster that affects both of the local sites.