zSeries Global Mirror (XRC)
Extended Remote Copy (XRC a.k.a. zSeries Global Mirror) is IBM's high-end solution for asynchronous Copy Services. XRC is supported by all IBM, HDS and EMC disk subsystems. The mirroring is done by a z/OS software component, called the System Data Mover (SDM) and is asynchronous to write operations issued by the Production Systems to the Primary Disk Subsystems.
Sizing an XRC installation involves the usual bandwidth planning just like for other asynchronous solutions. As XRC uses a System Data Mover with Readers to retrieve the data from the primary subsystems, more aspects are involved in XRC planning, however. Write activity must be balanced across LCUs and readers, and care must be taken to design the secondary subsystems such that they can handle the FlashCopy overhead.
You may also want to review the section on the IBM site dedicated to GDPS, and our summary of GDPS.
IntelliMagic provides a white paper specifically on XRC that you can request here.
In our products
IntelliMagic Vision provides extensive support for planning and monitoring XRC installations, both to from a bandwidth management perspective and a service level perspective. With IntelliMagic Vision you can monitor performance at the reader level, both at the primary and the secondary side. IntelliMagic Vision can be used in the planning phase of XRC implementations as well during the implementation phase.
When XRC is implemented with GDPS, you can use the GDPS GEOXPARM data set directly to view performance at the reader level, and to assess a proper GEOXPARM design even before GDPS XRC is implemented!
IntelliMagic Direction can predict the impact of XRC on the primary subsystem utilization for IBM controllers.