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## 5.3.7 z/OS Global Mirror 

z/OS Global Mirror , which was known as Extended Remote Copy (XRC), is a copy function that is available for the z/OS operating system. The basic operational characteristics of z/OS Global Mirror are shown in Figure 5-6. 

<img src='content_image/999794.jpg'>

It involves the System Data Mover (SDM), which is part of DFSMSdfp. DFSMSdfp in turn is a part of z/OS. z/OS Global Mirror maintains a consistent copy of the data asynchronously at a remote location. It can be implemented over unlimited distances. It is a combined hardware and software solution that offers data integrity and data availability that can be used as part of business continuance solutions, for workload movement, and for data migration. 

The z/OS Global Mirror function is an optional licensed function (Copy Services (CS)) of the DS8900F that enables the SDM to communicate with the primary DS8900F. No Copy Services license is required for the storage system in site H2. It can be any storage system that is supported by z/OS. However, consider that you might want to reverse the mirror, in which case your auxiliary storage system needs a Copy Services license as well. 

