This IBM® Redpaper publication describes the Incremental Resynchronization (IR) enhancements to the z/OS® Global Mirror (zGM) copy function when used in conjunction with Metro Mirror in a multiple target three-site solution.

This three-site mirroring solution is often simply called MzGM. zGM was previously known as Extended Remote Copy (XRC). The new name is, as the title for this paper indicates, z/OS Metro/Global Mirror Incremental Resync or, for short, RMZ Resync.